Question

A shopkeeper has 10 copies of each of nine different books, then number of ways in which at least one book can be selected is

• A. $9^{11}-1$
• B. ${10}^{10}-1$
• C. ${11}^9-1$
• D. ${10}^9$

Answer 1

The correct option is C ${11}^9-1$

$\underset{10}{\underset{}{B_1}}\underset{10}{\underset{}{B_2}}\underset{10}{\underset{}{B_3}}\cdots \underset{10}{\underset{}{B_9}}$
Selection of atleast one book
$\underset{9times}{\underset{}{(10+1)(10+1)\cdots (10+1)}}-1={11}^9-1$