Question

A library shelf contains ten novel and eight biographies. In how many ways can a borrower choose three novels and two biographers?

Answer 1

Answer:

Explanation:

Let the 10 novels be, N1,N2,N3,N4,N5 ,N6,N7,N8,N9,N10

And 8 biographies be, B1,B2,B3,B4,B5,B6,B7,B8

Now the 10 novels can be arranged in 10! and there is | N1 | N2 | N3 | N4 | N5 | |N7|N8|N9|N10  

12 gaps in which we can place the biography book a/q to question,this can be done in 12c8 × 8!

Now total number of ways = 10!×12c8 × 8!