Chapter 15, Problem 13E

To determine

To find: the probability that a kid who goes to the doctor has a sore throat and a fever.

Answer to Problem 13E

0.21

Explanation of Solution

Given:

  $P\left(F\right)=0.7$

Formula used:

  $P\left(S/F\right)=\frac{P\left(S\cap F\right)}{P\left(F\right)}$

Calculation:

Let S shows that kid has sore throat.

Let F shows that kid has Fever.

  $\begin{array}{c}P\left(S\cap F\right)=P\left(S/F\right)\times P\left(F\right)\\ =\left(0.3\right)\left(0.7\right)\\ =0.21\end{array}$

Therefore 21% of kids have sore throat and fever.