Chapter 13.3, Problem 24E

To determine

To find: The probability of $P\left(\text{not}\text{rock}\right)$ .

Answer to Problem 24E

The probability of $P\left(\text{not}\text{rock}\right)$ is $\frac{209}{260}$ .

Explanation of Solution

The number of rapare $10$ .

The number of rockare $18$ .

The number of countryare $8$ .

The number of pops are $4$

The probability of the successful outcome of an event is given by,

  $P\left(s\right)=\frac{s}{s+f}$

The $P\left(\text{1}\text{rap}\text{and}\text{1}\text{rock}\right)$ is calculated as,

  $\begin{array}{c}P\left(\text{not}\text{rock}\right)=1-\frac{C\left(18,1\right)}{C\left(40,2\right)}\\ =1-\frac{51}{260}\\ =\frac{209}{260}\end{array}$

Therefore, the probability of $P\left(\text{not}\text{rock}\right)$ is $\frac{209}{260}$ .