Concept-wise Practice

class 11 MCQ Questions for Class 11

class 11 se related questions ko ek jagah revise karein. Har question me bilingual content, answer feedback aur explanation available hai.

Practice Questions

2918 questions tagged with class 11.

\(-725^\circ\) का सबसे छोटा धनात्मक सह-टर्मिनल कोण कौन-सा है?

Which is the least positive coterminal angle of \(-725^\circ\)?

Explanation opens after your attempt
Correct Answer

D. \(355^\circ\)

Step 1

Concept

Adding \(360^\circ\) three times to \(-725^\circ\) gives \(355^\circ\). In exams, keep the answer between \(0^\circ\) and \(360^\circ\).

Step 2

Why this answer is correct

The correct answer is D. \(355^\circ\). Adding \(360^\circ\) three times to \(-725^\circ\) gives \(355^\circ\). In exams, keep the answer between \(0^\circ\) and \(360^\circ\).

Step 3

Exam Tip

\(-725^\circ\) में (3) बार \(360^\circ\) जोड़ने पर \(355^\circ\) मिलता है। परीक्षा में उत्तर को \(0^\circ\) से \(360^\circ\) के बीच रखें।

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\(\frac{7\pi}{12}\) रेडियन का डिग्री माप क्या है?

What is the degree measure of \(\frac{7\pi}{12}\) radians?

Explanation opens after your attempt
Correct Answer

C. \(105^\circ\)

Step 1

Concept

Multiplying radians by \(180^\circ/\pi\) gives \(105^\circ\). In exams, cancel \(\pi\) directly.

Step 2

Why this answer is correct

The correct answer is C. \(105^\circ\). Multiplying radians by \(180^\circ/\pi\) gives \(105^\circ\). In exams, cancel \(\pi\) directly.

Step 3

Exam Tip

रेडियन को \(180^\circ/\pi\) से गुणा करने पर \(105^\circ\) मिलता है। परीक्षा में \(\pi\) को सीधे काटें।

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\(112^\circ 30'\) को रेडियन में बदलने पर सही मान क्या होगा?

What is the correct radian measure of \(112^\circ 30'\)?

Explanation opens after your attempt
Correct Answer

B. (5\pi8)

Step 1

Concept

\(112^\circ 30'\) means \(112.5^\circ\), so the value is \(5\pi/8\). In exams, first convert minutes into degrees.

Step 2

Why this answer is correct

The correct answer is B. \(5\pi / 8\). \(112^\circ 30'\) means \(112.5^\circ\), so the value is \(5\pi/8\). In exams, first convert minutes into degrees.

Step 3

Exam Tip

\(112^\circ 30'\) का अर्थ \(112.5^\circ\) है, इसलिए मान \(5\pi/8\) मिलता है। परीक्षा में मिनट को पहले डिग्री में बदलें।

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कक्षा 11 में ligase enzymes को किन दो contexts में याद रखना चाहिए?

In Class 11 in which two contexts should ligase enzymes be remembered?

Explanation opens after your attempt
Correct Answer

A. recombinant DNA और DNA replicationRecombinant DNA and DNA replication

Step 1

Concept

Ligase joins fragments in recombinant DNA and joins Okazaki fragments in replication. Both exam contexts are important.

Step 2

Why this answer is correct

The correct answer is A. recombinant DNA और DNA replication / Recombinant DNA and DNA replication. Ligase joins fragments in recombinant DNA and joins Okazaki fragments in replication. Both exam contexts are important.

Step 3

Exam Tip

Ligase recombinant DNA में fragments जोड़ता है और replication में Okazaki fragments जोड़ता है। ये दोनों exam contexts महत्वपूर्ण हैं।

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क्लास 11 जैव प्रौद्योगिकी में लाइगेज को किससे सबसे अधिक जोड़ा जाता है?

In Class 11 biotechnology ligase is most associated with what?

Explanation opens after your attempt
Correct Answer

A. डीएनए खंडों की joiningJoining of DNA fragments

Step 1

Concept

Ligase joins DNA fragments. In biotechnology it is linked with cloning and recombinant DNA.

Step 2

Why this answer is correct

The correct answer is A. डीएनए खंडों की joining / Joining of DNA fragments. Ligase joins DNA fragments. In biotechnology it is linked with cloning and recombinant DNA.

Step 3

Exam Tip

लाइगेज डीएनए fragments को जोड़ता है। जैव प्रौद्योगिकी में यह cloning और recombinant DNA से जुड़ा है।

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restriction enzymes को molecular scissors कहने का सबसे सही कारण क्या है?

What is the best reason for calling restriction enzymes molecular scissors?

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Correct Answer

A. वे DNA molecules को cut करते हैंThey cut DNA molecules

Step 1

Concept

The name molecular scissors comes from their DNA cutting function. This is a basic term in Class 11 biotechnology.

Step 2

Why this answer is correct

The correct answer is A. वे DNA molecules को cut करते हैं / They cut DNA molecules. The name molecular scissors comes from their DNA cutting function. This is a basic term in Class 11 biotechnology.

Step 3

Exam Tip

Molecular scissors नाम DNA cutting function के कारण है। यह Class 11 biotechnology का basic term है।

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कौन सा विकल्प क्लास 11 जैव प्रौद्योगिकी में प्रतिबंध एंजाइमों का सबसे अच्छा सार देता है?

Which option best summarizes restriction enzymes in Class 11 biotechnology?

Explanation opens after your attempt
Correct Answer

A. डीएनए को विशेष स्थलों पर काटने वाले जीवाणु एंजाइमBacterial enzymes that cut DNA at specific sites

Step 1

Concept

Restriction enzymes are bacterial-origin DNA-cutting tools. This is the main summary of the topic.

Step 2

Why this answer is correct

The correct answer is A. डीएनए को विशेष स्थलों पर काटने वाले जीवाणु एंजाइम / Bacterial enzymes that cut DNA at specific sites. Restriction enzymes are bacterial-origin DNA-cutting tools. This is the main summary of the topic.

Step 3

Exam Tip

प्रतिबंध एंजाइम जीवाणु स्रोत के डीएनए-काटने वाले उपकरण हैं। यही इस टॉपिक का मुख्य सार है।

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प्रतिबंध एंजाइम मुख्य रूप से किस काम के लिए उपयोग किए जाते हैं?

What are restriction enzymes mainly used for?

Explanation opens after your attempt
Correct Answer

A. डीएनए को विशेष स्थानों पर काटनाCutting DNA at specific sites

Step 1

Concept

Restriction enzymes cut DNA at specific recognition sites. For exams remember them as molecular scissors of biotechnology.

Step 2

Why this answer is correct

The correct answer is A. डीएनए को विशेष स्थानों पर काटना / Cutting DNA at specific sites. Restriction enzymes cut DNA at specific recognition sites. For exams remember them as molecular scissors of biotechnology.

Step 3

Exam Tip

प्रतिबंध एंजाइम डीएनए को विशेष पहचान स्थलों पर काटते हैं। परीक्षा में इन्हें जैव प्रौद्योगिकी की आणविक कैंची याद रखें।

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(8) अलग-अलग लोगों को पंक्ति में बैठाना है। (A) और (B) साथ हों तथा (C) और (D) भी साथ हों, तो व्यवस्थाओं की संख्या कितनी होगी?

(8) distinct people are seated in a row. If (A) and (B) sit together and (C) and (D) also sit together, how many arrangements are possible?

Explanation opens after your attempt
Correct Answer

A. (2880)

Step 1

Concept

Treat (AB) and (CD) as two blocks; (6) objects can be arranged in (6!) ways and the blocks internally in \(2!\times2!\) ways. Exam tip: with multiple blocks, count each block's internal order.

Step 2

Why this answer is correct

The correct answer is A. (2880). Treat (AB) and (CD) as two blocks; (6) objects can be arranged in (6!) ways and the blocks internally in \(2!\times2!\) ways. Exam tip: with multiple blocks, count each block's internal order.

Step 3

Exam Tip

(AB) और (CD) को दो खंड मानें; कुल (6) वस्तुएं (6!) तरीकों से और दोनों खंडों के अंदर \(2!\times2!\) तरीके हैं। परीक्षा में कई blocks हों तो हर block का internal order गिनें।

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अंकों (0,1,2,3,4,5,6) से बिना पुनरावृत्ति (4)-अंकीय संख्याएं बनानी हैं जिनमें (0) शामिल हो लेकिन अंतिम अंक (0) न हो। कितनी संख्याएं बनेंगी?

Using digits (0,1,2,3,4,5,6) without repetition, how many (4)-digit numbers include (0) but do not end in (0)?

Explanation opens after your attempt
Correct Answer

B. (300)

Step 1

Concept

Zero can occupy only the hundreds or tens place, giving (2) choices; the other (3) places are filled from (6) nonzero digits in \(^{6}P_{3}\) ways. Exam tip: decide the allowed positions of (0) first.

Step 2

Why this answer is correct

The correct answer is B. (300). Zero can occupy only the hundreds or tens place, giving (2) choices; the other (3) places are filled from (6) nonzero digits in \(^{6}P_{3}\) ways. Exam tip: decide the allowed positions of (0) first.

Step 3

Exam Tip

(0) को केवल सैकड़ों या दहाइयों के स्थान पर रख सकते हैं, यानी (2) तरीके; फिर बाकी (3) स्थान (6) nonzero अंकों से \(^{6}P_{3}\) तरीकों से भरते हैं। परीक्षा में (0) की allowed positions पहले तय करें।

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(4) अलग-अलग दंपतियों को पंक्ति में बैठाना है। हर दंपति साथ बैठे और पुरुष हमेशा अपनी पत्नी के बाएं बैठे, तो व्यवस्थाओं की संख्या कितनी है?

(4) distinct couples are seated in a row. Each couple sits together and the husband always sits to the left of his wife. How many arrangements are possible?

Explanation opens after your attempt
Correct Answer

A. (24)

Step 1

Concept

Treat each couple as one block with fixed internal order, so only the (4!) blocks are arranged. Exam tip: do not multiply by (2!) when internal order is fixed.

Step 2

Why this answer is correct

The correct answer is A. (24). Treat each couple as one block with fixed internal order, so only the (4!) blocks are arranged. Exam tip: do not multiply by (2!) when internal order is fixed.

Step 3

Exam Tip

हर दंपति को निश्चित अंदरूनी क्रम वाला एक खंड मानें, इसलिए केवल (4!) खंडों को सजाना है। परीक्षा में internal order fixed हो तो (2!) न लगाएं।

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(7) अलग-अलग वस्तुओं की पंक्ति में (A), (B), (C) का सापेक्ष क्रम (A) फिर (B) फिर (C) होना चाहिए। कितनी व्यवस्थाएं होंगी?

In a row of (7) distinct objects, the relative order of (A), (B), (C) must be (A) then (B) then (C). How many arrangements are possible?

Explanation opens after your attempt
Correct Answer

A. (840)

Step 1

Concept

Among total (7!) arrangements, the (3!) relative orders of (A,B,C) are equally likely, so \(\frac{7!}{3!}\) are valid. Exam tip: divide by factorial for fixed relative order.

Step 2

Why this answer is correct

The correct answer is A. (840). Among total (7!) arrangements, the (3!) relative orders of (A,B,C) are equally likely, so \(\frac{7!}{3!}\) are valid. Exam tip: divide by factorial for fixed relative order.

Step 3

Exam Tip

कुल (7!) व्यवस्थाओं में (A,B,C) के (3!) सापेक्ष क्रम समान हैं, इसलिए \(\frac{7!}{3!}\) मान्य हैं। परीक्षा में fixed relative order के लिए factorial से divide करें।

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(5) अलग-अलग सफेद और (3) अलग-अलग काली गेंदें गोल घेरे में रखनी हैं। कोई दो काली गेंदें साथ न हों, तो व्यवस्थाओं की संख्या कितनी है?

(5) distinct white balls and (3) distinct black balls are placed around a circle. If no two black balls are adjacent, how many arrangements are possible?

Explanation opens after your attempt
Correct Answer

A. (2880)

Step 1

Concept

First arrange the (5) white balls around a circle in ((5-1)!) ways, then place (3) black balls in \(^{5}P_{3}\) circular gaps. Exam tip: in circular gaps, arrange the base objects first.

Step 2

Why this answer is correct

The correct answer is A. (2880). First arrange the (5) white balls around a circle in ((5-1)!) ways, then place (3) black balls in \(^{5}P_{3}\) circular gaps. Exam tip: in circular gaps, arrange the base objects first.

Step 3

Exam Tip

पहले (5) सफेद गेंदों की गोल व्यवस्था ((5-1)!) है, फिर (5) gaps में (3) काली गेंदें \(^{5}P_{3}\) तरीकों से रखी जाती हैं। परीक्षा में circular gaps में सफेद वस्तुओं को पहले fix करें।

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(8) अलग-अलग कारों को (10) पार्किंग स्थानों में लगाना है। दो विशेष कारें adjacent स्थानों में न लगें, तो कितने तरीके होंगे?

(8) distinct cars are parked in (10) parking spots. If two special cars must not be in adjacent spots, how many ways are possible?

Explanation opens after your attempt
Correct Answer

B. (1451520)

Step 1

Concept

Subtract adjacent-special-car cases \(9\times2!\times{}^{8}P_{6}\) from total \(^{10}P_{8}\). Exam tip: when parking spots are distinct, start from total arrangements.

Step 2

Why this answer is correct

The correct answer is B. (1451520). Subtract adjacent-special-car cases \(9\times2!\times{}^{8}P_{6}\) from total \(^{10}P_{8}\). Exam tip: when parking spots are distinct, start from total arrangements.

Step 3

Exam Tip

कुल \(^{10}P_{8}\) से special cars adjacent वाली \(9\times2!\times{}^{8}P_{6}\) व्यवस्थाएं घटाएं। परीक्षा में parking spots distinct हों तो पहले कुल arrangements लें।

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शब्द (PERMUTE) के अक्षरों की व्यवस्थाओं में (P) और (E) दोनों सिरों पर हों, तो व्यवस्थाओं की संख्या कितनी है?

In arrangements of the letters of (PERMUTE), how many have (P) and an (E) at the two ends?

Explanation opens after your attempt
Correct Answer

B. (240)

Step 1

Concept

Choose the end for (P) and (E) in (2) ways; the remaining (5) letters include (E) repeated twice, so there are \(\frac{5!}{2!}\) arrangements. Exam tip: divide for a repeated end-letter left inside.

Step 2

Why this answer is correct

The correct answer is B. (240). Choose the end for (P) and (E) in (2) ways; the remaining (5) letters include (E) repeated twice, so there are \(\frac{5!}{2!}\) arrangements. Exam tip: divide for a repeated end-letter left inside.

Step 3

Exam Tip

एक सिरा (P) के लिए और दूसरा (E) के लिए (2) तरीकों से चुने; बाकी (5) अक्षरों में (E) दो बार है, इसलिए \(\frac{5!}{2!}\) व्यवस्थाएं हैं। परीक्षा में repeated end-letter बच जाने पर उसका factorial divide करें।

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(6) अलग-अलग प्रश्नों को (6) क्रमांकित स्थानों में लगाना है। प्रश्न (1) और प्रश्न (2) के बीच ठीक (1) प्रश्न हो, तो व्यवस्थाओं की संख्या कितनी है?

(6) distinct questions are arranged in (6) numbered positions. If exactly (1) question lies between question (1) and question (2), how many arrangements are possible?

Explanation opens after your attempt
Correct Answer

B. (192)

Step 1

Concept

There are (4) position pairs at distance (2) and (2!) orders for questions (1) and (2), and the remaining (4) questions arrange in (4!) ways. Exam tip: exactly one between means position difference (2).

Step 2

Why this answer is correct

The correct answer is B. (192). There are (4) position pairs at distance (2) and (2!) orders for questions (1) and (2), and the remaining (4) questions arrange in (4!) ways. Exam tip: exactly one between means position difference (2).

Step 3

Exam Tip

प्रश्न (1) और (2) के लिए दूरी (2) वाले (4) position-pairs और (2!) क्रम हैं, बाकी (4) प्रश्न (4!) तरीकों से लगेंगे। परीक्षा में exactly one between का अर्थ position difference (2) है।

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(9) अलग-अलग लोगों की पंक्ति में (A) और (B) साथ हों, पर (C) उनके किसी भी तरफ तुरंत पास न हो। कितनी व्यवस्थाएं होंगी?

In a row of (9) distinct people, (A) and (B) are together, but (C) is not immediately next to either of them. How many arrangements are possible?

Explanation opens after your attempt
Correct Answer

D. (10080)

Step 1

Concept

Form an (AB) block among (8) objects, then subtract cases where (C) is adjacent to the block on either outside side; total is (2!\times\(8!-2\times7!\)). Exam tip: compound restrictions may need both block and subtraction.

Step 2

Why this answer is correct

The correct answer is D. (10080). Form an (AB) block among (8) objects, then subtract cases where (C) is adjacent to the block on either outside side; total is (2!\times\(8!-2\times7!\)). Exam tip: compound restrictions may need both block and subtraction.

Step 3

Exam Tip

(AB) खंड बनाकर (8) वस्तुओं की व्यवस्थाएं लें, फिर (C) के खंड से adjacent होने वाले (2) बाहरी स्थानों को घटाएं; कुल (2!\times\(8!-2\times7!\)) है। परीक्षा में compound restriction में block और subtraction दोनों लग सकते हैं।

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अंकों (2,3,4,5,6,7,8,9) से बिना पुनरावृत्ति (4)-अंकीय संख्याएं बनानी हैं। कितनी संख्याएं (5000) से बड़ी और सम होंगी?

Using digits (2,3,4,5,6,7,8,9) without repetition, how many (4)-digit numbers greater than (5000) and even can be formed?

Explanation opens after your attempt
Correct Answer

A. (400)

Step 1

Concept

The thousands digit must be from (5,6,7,8,9), and the units digit must be even; case-wise counting gives (400). Exam tip: count overlapping digit choices case by case.

Step 2

Why this answer is correct

The correct answer is A. (400). The thousands digit must be from (5,6,7,8,9), and the units digit must be even; case-wise counting gives (400). Exam tip: count overlapping digit choices case by case.

Step 3

Exam Tip

हजारों का अंक (5,6,7,8,9) में से और इकाई अंक सम होना चाहिए; leading और ending cases अलग गिनने पर (400) मिलता है। परीक्षा में overlapping digit choices को case-wise गिनें।

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(8) अलग-अलग अक्षरों से (5)-अक्षरीय शब्द बनाने हैं। दो विशेष अक्षर दोनों शामिल हों और adjacent न हों, तो कितने शब्द बनेंगे?

(5)-letter words are formed from (8) distinct letters. If two special letters must both be included and not adjacent, how many words are possible?

Explanation opens after your attempt
Correct Answer

C. (2160)

Step 1

Concept

Choose the other (3) letters from (6), then subtract adjacent special-pair arrangements \(2!\times4!\) from total (5!). Exam tip: handle inclusion and adjacency restrictions separately.

Step 2

Why this answer is correct

The correct answer is C. (2160). Choose the other (3) letters from (6), then subtract adjacent special-pair arrangements \(2!\times4!\) from total (5!). Exam tip: handle inclusion and adjacency restrictions separately.

Step 3

Exam Tip

बाकी (3) अक्षर (6) में से चुनें, फिर (5!) कुल व्यवस्थाओं से special pair adjacent वाली \(2!\times4!\) व्यवस्थाएं घटाएं। परीक्षा में शामिल और adjacent restriction को अलग-अलग संभालें।

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(7) अलग-अलग पुरस्कार (7) छात्रों में बांटने हैं। ठीक (2) विशेष पुरस्कार अपने निर्धारित छात्रों को मिलें, तो कितने तरीके होंगे?

(7) distinct prizes are assigned to (7) students. How many assignments have exactly (2) prizes going to their designated students?

Explanation opens after your attempt
Correct Answer

B. (1854)

Step 1

Concept

Choose the (2) correctly assigned prizes in \(\binom{7}{2}\) ways and derange the remaining (5), giving (!5=44). Exam tip: use derangement for exactly correct cases.

Step 2

Why this answer is correct

The correct answer is B. (1854). Choose the (2) correctly assigned prizes in \(\binom{7}{2}\) ways and derange the remaining (5), giving (!5=44). Exam tip: use derangement for exactly correct cases.

Step 3

Exam Tip

सही जाने वाले (2) पुरस्कार \(\binom{7}{2}\) तरीकों से चुनें और बाकी (5) का derangement (!5=44) है। परीक्षा में exactly correct cases के लिए derangement का प्रयोग करें।

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शब्द (MISSISSIPPI) के अक्षरों की कुल अलग-अलग व्यवस्थाओं की संख्या कितनी है?

How many distinct arrangements are possible using all letters of (MISSISSIPPI)?

Explanation opens after your attempt
Correct Answer

A. (34650)

Step 1

Concept

There are (11) letters; (I) occurs four times, (S) occurs four times, and (P) occurs twice, so the count is \(\frac{11!}{4!,4!,2!}\). Exam tip: recheck repeated-letter counts.

Step 2

Why this answer is correct

The correct answer is A. (34650). There are (11) letters; (I) occurs four times, (S) occurs four times, and (P) occurs twice, so the count is \(\frac{11!}{4!,4!,2!}\). Exam tip: recheck repeated-letter counts.

Step 3

Exam Tip

कुल (11) अक्षर हैं; (I) चार, (S) चार और (P) दो बार आते हैं, इसलिए \(\frac{11!}{4!,4!,2!}\) है। परीक्षा में समान अक्षरों की गिनती दोबारा जांचें।

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(10) अलग-अलग लोगों की गोल बैठक में (A) और (B) ठीक विपरीत सीटों पर बैठें, तो व्यवस्थाओं की संख्या कितनी है?

In a circular seating of (10) distinct people on equally spaced seats, (A) and (B) must sit exactly opposite each other. How many arrangements are possible?

Explanation opens after your attempt
Correct Answer

A. (80640)

Step 1

Concept

Fix (A); the opposite seat for (B) is fixed, and the remaining (8) people can be arranged in (8!) ways. Exam tip: fix one person to remove circular symmetry.

Step 2

Why this answer is correct

The correct answer is A. (80640). Fix (A); the opposite seat for (B) is fixed, and the remaining (8) people can be arranged in (8!) ways. Exam tip: fix one person to remove circular symmetry.

Step 3

Exam Tip

(A) को स्थिर करें, (B) की विपरीत सीट निश्चित है, और बाकी (8) लोग (8!) तरीकों से बैठते हैं। परीक्षा में circular symmetry हटाने के लिए एक व्यक्ति को स्थिर करें।

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(6) अलग-अलग अंगूठियों को (4) अलग-अलग उंगलियों में पहनाना है, प्रत्येक उंगली पर अधिकतम एक अंगूठी हो। कितने तरीके होंगे?

(6) distinct rings are to be worn on (4) distinct fingers, with at most one ring on each finger. How many ways are possible?

Explanation opens after your attempt
Correct Answer

A. (360)

Step 1

Concept

We assign (4) of the (6) rings to (4) distinct fingers with order, so \(^{6}P_{4}=360\). Exam tip: distinct fingers require permutations.

Step 2

Why this answer is correct

The correct answer is A. (360). We assign (4) of the (6) rings to (4) distinct fingers with order, so \(^{6}P_{4}=360\). Exam tip: distinct fingers require permutations.

Step 3

Exam Tip

(6) अंगूठियों में से (4) को (4) अलग-अलग उंगलियों पर क्रम सहित रखना है, इसलिए \(^{6}P_{4}=360\)। परीक्षा में distinct fingers होने पर permutation लगती है।

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अंकों (0,1,2,3,4,5,6,7,8) से बिना पुनरावृत्ति (6)-अंकीय संख्याएं बनें जिनमें (0) और (8) दोनों शामिल हों। कितनी संख्याएं बनेंगी?

Using digits (0,1,2,3,4,5,6,7,8) without repetition, how many (6)-digit numbers include both (0) and (8)?

Explanation opens after your attempt
Correct Answer

B. (13440)

Step 1

Concept

Choose the other (4) digits with (0) and (8) in \(\binom{7}{4}\) ways; for each selection subtract (5!) leading-zero cases from (6!). Exam tip: leading zero correction is mandatory.

Step 2

Why this answer is correct

The correct answer is B. (13440). Choose the other (4) digits with (0) and (8) in \(\binom{7}{4}\) ways; for each selection subtract (5!) leading-zero cases from (6!). Exam tip: leading zero correction is mandatory.

Step 3

Exam Tip

(0) और (8) के साथ बाकी (4) अंक \(\binom{7}{4}\) तरीकों से चुनें; प्रत्येक चयन में कुल (6!) से first zero वाले (5!) घटाएं। परीक्षा में leading zero का correction अनिवार्य है।

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(5) अलग-अलग भारतीय और (5) अलग-अलग विदेशी छात्रों को पंक्ति में बैठाना है। वे nationality के अनुसार alternate बैठें, तो व्यवस्थाओं की संख्या कितनी है?

(5) distinct Indian and (5) distinct foreign students are seated in a row. If they sit alternately by nationality, how many arrangements are possible?

Explanation opens after your attempt
Correct Answer

A. (28800)

Step 1

Concept

There are (2) alternate patterns, and in each pattern Indians can be arranged in (5!) ways and foreigners in (5!) ways. Exam tip: equal groups in alternate arrangement give (2) patterns.

Step 2

Why this answer is correct

The correct answer is A. (28800). There are (2) alternate patterns, and in each pattern Indians can be arranged in (5!) ways and foreigners in (5!) ways. Exam tip: equal groups in alternate arrangement give (2) patterns.

Step 3

Exam Tip

दो alternate patterns संभव हैं और प्रत्येक में भारतीय (5!) तथा विदेशी (5!) तरीकों से बैठते हैं। परीक्षा में बराबर समूहों के alternate arrangement में (2) patterns होते हैं।

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(7) अलग-अलग वस्तुओं को पंक्ति में सजाना है। (A) हमेशा (B) के बाएं हो, पर जरूरी नहीं कि साथ हो। कितनी व्यवस्थाएं होंगी?

(7) distinct objects are arranged in a row. If (A) must always be to the left of (B), not necessarily adjacent, how many arrangements are possible?

Explanation opens after your attempt
Correct Answer

A. (2520)

Step 1

Concept

In total (7!) arrangements, the two relative orders of (A) and (B) are equally likely, so half are valid. Exam tip: use symmetry for relative order conditions like left of.

Step 2

Why this answer is correct

The correct answer is A. (2520). In total (7!) arrangements, the two relative orders of (A) and (B) are equally likely, so half are valid. Exam tip: use symmetry for relative order conditions like left of.

Step 3

Exam Tip

कुल (7!) व्यवस्थाओं में (A) और (B) के दो सापेक्ष क्रम समान रूप से संभव हैं, इसलिए आधी व्यवस्थाएं मान्य हैं। परीक्षा में left of जैसी relative order शर्त के लिए symmetry प्रयोग करें।

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शब्द (ALGEBRA) के अक्षरों से बनने वाली व्यवस्थाओं में सभी स्वर alphabetical order में रहें, तो कितनी व्यवस्थाएं होंगी?

In arrangements of the letters of (ALGEBRA), how many have all vowels in alphabetical order?

Explanation opens after your attempt
Correct Answer

D. (210)

Step 1

Concept

Total arrangements are \(\frac{7!}{2!}\), and among the (4) relative orders of vowels only (1) order is allowed, so divide by (4!). Exam tip: divide by the factorial when relative order is fixed.

Step 2

Why this answer is correct

The correct answer is D. (210). Total arrangements are \(\frac{7!}{2!}\), and among the (4) relative orders of vowels only (1) order is allowed, so divide by (4!). Exam tip: divide by the factorial when relative order is fixed.

Step 3

Exam Tip

कुल व्यवस्थाएं \(\frac{7!}{2!}\) हैं और (4) स्वरों के सापेक्ष क्रमों में केवल (1) क्रम स्वीकार्य है, इसलिए (4!) से भाग दें। परीक्षा में relative order fixed हो तो संबंधित factorial से divide करें।

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(6) अलग-अलग लोगों को (8) क्रमांकित सीटों में बैठाना है। (A) और (B) के बीच कम से कम (2) खाली सीट या व्यक्ति हों, तो कितनी व्यवस्थाएं होंगी?

(6) distinct people are to be seated in (8) numbered seats. How many arrangements have at least (2) seats or people between (A) and (B)?

Explanation opens after your attempt
Correct Answer

B. (16800)

Step 1

Concept

First choose ordered seat pairs for (A,B) with distance at least (3); there are (42) such pairs, then seat the remaining (4) people in \(^{6}P_{4}\) ways. Exam tip: position-pair counting is useful for numbered seats.

Step 2

Why this answer is correct

The correct answer is B. (16800). First choose ordered seat pairs for (A,B) with distance at least (3); there are (42) such pairs, then seat the remaining (4) people in \(^{6}P_{4}\) ways. Exam tip: position-pair counting is useful for numbered seats.

Step 3

Exam Tip

पहले (A,B) के सीट-जोड़ों में दूरी कम से कम (3) रखें; ऐसे ordered pairs (42) हैं, फिर बाकी (4) लोग \(^{6}P_{4}\) तरीकों से बैठते हैं। परीक्षा में numbered seats में position-pair गिनना उपयोगी है।

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(5) अलग-अलग गणित और (4) अलग-अलग भौतिकी पुस्तकों को शेल्फ पर रखना है। कोई दो भौतिकी पुस्तकें साथ न हों, तो व्यवस्थाओं की संख्या कितनी है?

(5) distinct mathematics books and (4) distinct physics books are arranged on a shelf. If no two physics books are together, how many arrangements are possible?

Explanation opens after your attempt
Correct Answer

A. (86400)

Step 1

Concept

Arrange the (5) mathematics books in (5!) ways, then place the (4) physics books in \(^{6}P_{4}\) gaps. Exam tip: gaps are the safest method for no two together.

Step 2

Why this answer is correct

The correct answer is A. (86400). Arrange the (5) mathematics books in (5!) ways, then place the (4) physics books in \(^{6}P_{4}\) gaps. Exam tip: gaps are the safest method for no two together.

Step 3

Exam Tip

पहले (5) गणित पुस्तकें (5!) तरीकों से रखें, फिर (6) gaps में (4) भौतिकी पुस्तकें \(^{6}P_{4}\) तरीकों से रखें। परीक्षा में no two together के लिए gaps सबसे सुरक्षित तरीका है।

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शब्द (TRIANGLE) के अक्षरों की व्यवस्थाओं में (T) पहले और (E) अंतिम न हो, ऐसी व्यवस्थाओं की संख्या कितनी है?

In arrangements of the letters of (TRIANGLE), how many have (T) not first and (E) not last?

Explanation opens after your attempt
Correct Answer

B. (30960)

Step 1

Concept

Use inclusion-exclusion on total (8!), subtracting cases with (T) first and (E) last: (8!-7!-7!+6!). Exam tip: add back the overlap in two forbidden conditions.

Step 2

Why this answer is correct

The correct answer is B. (30960). Use inclusion-exclusion on total (8!), subtracting cases with (T) first and (E) last: (8!-7!-7!+6!). Exam tip: add back the overlap in two forbidden conditions.

Step 3

Exam Tip

कुल (8!) से (T) first और (E) last वाले मामलों को inclusion-exclusion से घटाएं, यानी (8!-7!-7!+6!)। परीक्षा में दो निषेध शर्तों में overlap जोड़ना न भूलें।

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