Question

Suppose the monthly charges for cell phone plans are normally distributed with mean and standard deviation $.(a) Draw a normal curve with the parameters labeled.(b) Shade the region that represents the proportion of plans that charge than $.(c) Suppose the area under the normal curve to the of X$ is 0.1587. Provide an interpretation of this result.

Answer 1

(a) From the information given in the question,

We will select a curve with 58 at its center which represents the mean and

`\begin{gathered} 58-17=41 \\ 58+17=75 \end{gathered}`

41 and 75 at the left and right sides. That is gotten by subtracting and adding the standard deviation of 17.

Hence the answer is Graph D

(b) The region that represents less than 41 is seen in graph B

Hence graph B is the answer

(c) Option A

The probability is 0.1587 that a randomly selected cell phone plan in this population is less than $41 per month