Tim must read 2 books from a list of 7 recommended books for his summer reading program. in how many different ways can tim choose 2 books from the 7 recommended books?

There are 21 ways Tim choose 2 books from the 7 recommended book

Solution:

Given that Tim must read 2 books from a list of 7 recommended books for his summer reading program

To find: different ways can Tim choose 2 books from the 7 recommended books

This is a combination problem

A combination is a selection of all or part of a set of objects, without regard to the order in which objects are selected

The formula for combinations is:

where n represents the number of items, and r represents the number of items being chosen at a time

Here we have to choose 2 books from 7 books

Therefore, n = 7 and r = 2

Substituting values in above formula, we get

For a number n, the factorial of n can be written as,

Therefore, we get

Thus there are 21 ways Tim choose 2 books from the 7 recommended book