Q. In how many ways can 5 books be selected out of 10 books, if two specific books are never selected?
A) 56
B) 65
C) 58
D) None of these
Explanation
(a)
Required number of ways $= \ ^{8}C_{5}$
$= \frac{8 \times 7 \times 6}{3 \times 2 \times 1} = 56$
The total number of ways a voter can vote
$= \ ^{8}C_{1} + \ ^{8}C_{2} + \ ^{8}C_{3} + \ ^{8}C_{4} + \ ^{8}C_{5}$
$= 8 + 28 + 56 + 70 + 56 = 218$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.