(8) विषयों में से (4) विषय चुनने हैं लेकिन गणित और जीवविज्ञान दोनों साथ में नहीं चुने जा सकते। कितने तरीके हैं?
From (8) subjects (4) subjects are to be selected but mathematics and biology cannot both be selected together. How many ways are there?
Explanation opens after your attempt
Correct Answer
C. (55)
Concept
Total ways are \(\binom{8}{4}=70\) and if both special subjects are included there are \(\binom{6}{2}=15\) ways. Hence (70-15=55).
Why this answer is correct
The correct answer is C. (55). Total ways are \(\binom{8}{4}=70\) and if both special subjects are included there are \(\binom{6}{2}=15\) ways. Hence (70-15=55).
Exam Tip
कुल \(\binom{8}{4}=70\) हैं और दोनों विशेष विषय साथ हों तो \(\binom{6}{2}=15\) हैं। इसलिए (70-15=55) है।
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