sec16 9 Mike owns 8 different mathematics books and 4 differ

sec16) #9

Mike owns 8 different mathematics books and 4 different computer science books and wish to fill 5 positions on a shelf. If the first 2 positions are to be occupied by math books and the last 3 by computer science books, in how many ways can this be done?

Solution

First two positions can be filled in C(8,2)*2=8*7=56 ways

Last three positions can be filled in C(4,3)*3!=4*6=24 ways

So total:56*24=1344 ways