Question

The number of ways of selecting $6$ books from a library which has $8$ books each on history, civics, Eco, and Geography is

• A. $36$
• B. $84$
• C. $66$
• D. None of these

Answer 1

The correct option is B $84$

We need to select $6$ books by selecting any number of books of a single subject (no. of books of any subject is more than the number of books we need). There are $4$ subjects.
This is equivalent to distributing $6$ sweets among $4$ boys.
This can be done in ${}^{6+4-1}{C}_{4-1}{=}^9{C}_3=84$ ways.
Hence, (B) is correct.