If all special students are included there are \(\binom{11}{4}=330\) ways and if all are excluded there are \(\binom{11}{7}=330\) ways. The total is (660).
Step 2
Why this answer is correct
The correct answer is B. (660). If all special students are included there are \(\binom{11}{4}=330\) ways and if all are excluded there are \(\binom{11}{7}=330\) ways. The total is (660).
Step 3
Exam Tip
सभी विशेष शामिल हों तो \(\binom{11}{4}=330\) और सभी बाहर हों तो \(\binom{11}{7}=330\) तरीके हैं। कुल (660) है।
For a failed triangle (3) points are chosen from the (10) collinear points. So the number is \(\binom{10}{3}\).
Step 2
Why this answer is correct
The correct answer is C. \(\binom{10}{3}\). For a failed triangle (3) points are chosen from the (10) collinear points. So the number is \(\binom{10}{3}\).
Step 3
Exam Tip
असफल त्रिभुज के लिए (10) समरेखीय बिंदुओं में से (3) चुने जाते हैं। इसलिए संख्या \(\binom{10}{3}\) है।
The (3) numbers are fixed and (2) are excluded. The remaining (5) numbers are chosen from (13), so \(\binom{13}{5}=1287\).
Step 2
Why this answer is correct
The correct answer is B. (1287). The (3) numbers are fixed and (2) are excluded. The remaining (5) numbers are chosen from (13), so \(\binom{13}{5}=1287\).
Step 3
Exam Tip
(3) संख्याएं तय हैं और (2) हट गई हैं। बाकी (5) संख्याएं (13) में से चुनी जाएंगी इसलिए \(\binom{13}{5}=1287\) है।
Chemistry is fixed and biology is excluded. Choose the remaining (4) subjects from (9) and subtract \(\binom{7}{2}\) selections containing both mathematics and physics to get (105).
Step 2
Why this answer is correct
The correct answer is A. (105). Chemistry is fixed and biology is excluded. Choose the remaining (4) subjects from (9) and subtract \(\binom{7}{2}\) selections containing both mathematics and physics to get (105).
Step 3
Exam Tip
रसायन तय और जीवविज्ञान हट गया है। बाकी (4) विषय (9) में से चुनें और गणित-भौतिकी दोनों वाले \(\binom{7}{2}\) चयन घटाएं तो (105) मिलते हैं।
The letter (a) is fixed and (b) is excluded. Choose (1) from (c,d) and (4) from the remaining (9), so \(\binom{2}{1}\binom{9}{4}=252\).
Step 2
Why this answer is correct
The correct answer is C. (252). The letter (a) is fixed and (b) is excluded. Choose (1) from (c,d) and (4) from the remaining (9), so \(\binom{2}{1}\binom{9}{4}=252\).
Step 3
Exam Tip
(a) तय है और (b) हट गया है। (c,d) में से (1) और शेष (9) में से (4) चुनेंगे इसलिए \(\binom{2}{1}\binom{9}{4}=252\) है।
Total ways are \(\binom{21}{7}=116280\). Removing all-white \(\binom{10}{7}=120\) and all-black \(\binom{11}{7}=330\) gives (115830).
Step 2
Why this answer is correct
The correct answer is B. (115830). Total ways are \(\binom{21}{7}=116280\). Removing all-white \(\binom{10}{7}=120\) and all-black \(\binom{11}{7}=330\) gives (115830).
Step 3
Exam Tip
कुल \(\binom{21}{7}=116280\) हैं। सभी सफेद \(\binom{10}{7}=120\) और सभी काली \(\binom{11}{7}=330\) हटाने पर (115830) मिलते हैं।
The element (1) is fixed so choose (5) elements from (12). Subtracting \(\binom{10}{3}=120\) cases containing both (5), (6) gives (792-120=672).
Step 2
Why this answer is correct
The correct answer is A. (672). The element (1) is fixed so choose (5) elements from (12). Subtracting \(\binom{10}{3}=120\) cases containing both (5), (6) gives (792-120=672).
Step 3
Exam Tip
(1) तय है इसलिए (5) तत्व (12) में से चुनेंगे। (5), (6) दोनों होने पर \(\binom{10}{3}=120\) घटाने से (792-120=672) मिलता है।
The elements (1), (2) are fixed and (3), (4) are excluded. The remaining (5) elements are chosen from (10), so \(\binom{10}{5}=252\).
Step 2
Why this answer is correct
The correct answer is B. (252). The elements (1), (2) are fixed and (3), (4) are excluded. The remaining (5) elements are chosen from (10), so \(\binom{10}{5}=252\).
Step 3
Exam Tip
(1) और (2) तय हैं तथा (3), (4) हट गए हैं। बाकी (5) तत्व (10) में से चुने जाएंगे इसलिए \(\binom{10}{5}=252\) है।
By Pascal's identity \(\binom{n}{r}+\binom{n}{r+1}=\binom{n+1}{r+1}\). Hence the answer is \(\binom{14}{7}\).
Step 2
Why this answer is correct
The correct answer is A. \(\binom{14}{7}\). By Pascal's identity \(\binom{n}{r}+\binom{n}{r+1}=\binom{n+1}{r+1}\). Hence the answer is \(\binom{14}{7}\).
Step 3
Exam Tip
पास्कल पहचान से \(\binom{n}{r}+\binom{n}{r+1}=\binom{n+1}{r+1}\) होता है। इसलिए उत्तर \(\binom{14}{7}\) है।
The number of pens can be (2), (3), (4), or (5). The total is \(\binom{10}{2}\binom{8}{5}+\binom{10}{3}\binom{8}{4}+\binom{10}{4}\binom{8}{3}+\binom{10}{5}\binom{8}{2}=29736\).
Step 2
Why this answer is correct
The correct answer is B. (29736). The number of pens can be (2), (3), (4), or (5). The total is \(\binom{10}{2}\binom{8}{5}+\binom{10}{3}\binom{8}{4}+\binom{10}{4}\binom{8}{3}+\binom{10}{5}\binom{8}{2}=29736\).
Step 3
Exam Tip
पेन (2), (3), (4) या (5) हो सकते हैं। कुल \(\binom{10}{2}\binom{8}{5}+\binom{10}{3}\binom{8}{4}+\binom{10}{4}\binom{8}{3}+\binom{10}{5}\binom{8}{2}=29736\) है।
The number of special students can be (3), (4), (5), or (6). The total is \(\binom{6}{3}\binom{11}{5}+\binom{6}{4}\binom{11}{4}+\binom{6}{5}\binom{11}{3}+\binom{6}{6}\binom{11}{2}=15235\).
Step 2
Why this answer is correct
The correct answer is D. (15235). The number of special students can be (3), (4), (5), or (6). The total is \(\binom{6}{3}\binom{11}{5}+\binom{6}{4}\binom{11}{4}+\binom{6}{5}\binom{11}{3}+\binom{6}{6}\binom{11}{2}=15235\).
Step 3
Exam Tip
विशेष छात्र (3), (4), (5) या (6) हो सकते हैं। कुल \(\binom{6}{3}\binom{11}{5}+\binom{6}{4}\binom{11}{4}+\binom{6}{5}\binom{11}{3}+\binom{6}{6}\binom{11}{2}=15235\) है।
One color is fixed and one is excluded. Choose the remaining (5) colors from (11) and subtract \(\binom{9}{5}\) selections missing both other colors to get (336).
Step 2
Why this answer is correct
The correct answer is A. (336). One color is fixed and one is excluded. Choose the remaining (5) colors from (11) and subtract \(\binom{9}{5}\) selections missing both other colors to get (336).
Step 3
Exam Tip
एक रंग तय और एक हट गया है। बाकी (5) रंग (11) में से चुनें और दोनों अन्य रंग न आने वाले \(\binom{9}{5}\) चयन घटाएं तो (336) मिलेगा।
The number of doctors will be (4), (5), (6), or (7). The total is \(\binom{11}{4}\binom{8}{3}+\binom{11}{5}\binom{8}{2}+\binom{11}{6}\binom{8}{1}+\binom{11}{7}=35442\).
Step 2
Why this answer is correct
The correct answer is D. (35442). The number of doctors will be (4), (5), (6), or (7). The total is \(\binom{11}{4}\binom{8}{3}+\binom{11}{5}\binom{8}{2}+\binom{11}{6}\binom{8}{1}+\binom{11}{7}=35442\).
Step 3
Exam Tip
डॉक्टरों की संख्या (4), (5), (6) या (7) होगी। कुल \(\binom{11}{4}\binom{8}{3}+\binom{11}{5}\binom{8}{2}+\binom{11}{6}\binom{8}{1}+\binom{11}{7}=35442\) है।
