# Suppose 61 newly created pairs of jeans are placed in a bin to be checked for quality. Of these, 5 will not be of high enough quality to sell. What is the chance that two pairs of jeans selected will be substandard?

##### 1 Answer
Apr 20, 2017

Let's take them out one by one.

#### Explanation:

The chance of the first one to be substandard is $\frac{5}{61}$

The chance of the second to be also substandard is $\frac{4}{60}$

So the chance of both of them being substandard is:
(this is an AND situation, so we MULTIPLY):

$\frac{5}{61} \times \frac{4}{60} = \frac{20}{3660} = \frac{1}{183}$

Extra:
The chance of only one to be found substandard is:

$\frac{5}{61} \times \frac{56}{60} + \frac{56}{61} \times \frac{5}{60}$. Why?