Chapter 12.8, Problem 7LC

To determine

To find: The error in the probability of yellow or letter.

Answer to Problem 7LC

The correct probability of yellow or letter is $\frac{4}{5}$ .

Explanation of Solution

The expression for probability of an event is given by,

  $P\left(E\right)=\frac{\text{Favorable}\text{Outcomes}}{\text{Possible}\text{outcomes}}$

The probability of $P\left(\text{yellow}\text{or}\text{letter}\right)$ is calculated as,

  $\begin{array}{c}P\left(\text{yellow}\text{or}\text{letter}\right)=P\left(\text{letter}\right)+P\left(\text{yellow}\right)-P\left(\text{yellow}\text{and}\text{letter}\right)\\ =\frac{3}{5}+\frac{2}{5}-\frac{1}{5}\\ =1-\frac{1}{5}\\ =\frac{4}{5}\end{array}$

Therefore, the correct probability of yellow or letter is $\frac{4}{5}$