Show steps To build a decorative fence around his patio Tom

To build a decorative fence around his patio, Tom needs four split rails. The lumber supply company has only seven in stock. How many ways may Tom choose the rails he needs?

Solution

The number of ways of selecting r oblectives from a set of n objectives is nC_r.

So that Tom can choose 4 split rails from 7 rails in the stock in 7C₄ = 35 ways