Q. From 12 books, the difference between number of ways a selection of 5 books when one specified book is always excluded and one specified book is always included, is
A) 64
B) 118
C) 132
D) 330
Explanation
(c)
Required number of ways
$= \ ^{11}C_{5} - \ ^{11}C_{4}$
$= \frac{11!}{5!6!} = \frac{11!}{4!7!} = 132$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.