Permutation and CombinationHard
Question
A student has to answer 10 out of 13 questions in an examination. The number of ways in which he can answer if he must answer atleast 3 of the first five questions is:
Options
A.276
B.267
C.13C10 - 5C3
D.5C3 . 8C7 + 5C4 . 8C6 + 8C5
Solution
Total number of required possibilities
5C3 . 8C7 + 5C4 . 8C6 + 5C5 . 8C5 . 5C5
= 5C3 . 8C7 + 5C4 . 8C6 + 8C6
= 13C10 - 5C3 = 276
5C3 . 8C7 + 5C4 . 8C6 + 5C5 . 8C5 . 5C5
= 5C3 . 8C7 + 5C4 . 8C6 + 8C6
= 13C10 - 5C3 = 276
Create a free account to view solution
View Solution FreeMore Permutation and Combination Questions
Total number of even divisors of 2079000 which are divisible by 15 are -...5 Indian & 5 American couples meet at a party & shake hands. If no wife shakes hands with her own husband & no Indian wi...The letters of the word "UDAYPUR" are written in all possible ways with or without meaning and these words are arranged ...The number of words which can be formed by using the letters of the word ′INDEPENDENCE′ so that both D occur...Number of ways of placing 5 different balls in 3 identical boxes (no box remains empty), is -...