Mike owns 7 different mathematics books and 6 different computer science books and wish to fill 5 positions on a shelf

Question

Mike owns 7 different mathematics books and 6 different computer science books and wish to fill 5 positions on a shelf. If the first 3 positions are to be occupied by math books and the last 2 by computer science books, in how many ways can this be done?

Answer 1

First 3 positions can be filled in 7C3 ways; last 2 positions can be filled in 6C2 ways.

 

Evaluate each of these two numbers, and MULTIPLY them to produce the answer.