Question

According to a report by Scarborough Research, the average monthly household cellular phone bill is $73. Suppose local monthly household cell phone bills are normally distributed with a standard deviation of $11.

a. What is the probability that a randomly selected monthly cell phone bill is less than $95?

Answer 1

The probability that a randomly selected monthly cell phone bill is less than $95 is 0.9772

Explanation:

The average monthly household cellular phone bill is $73.

`\mu = 73`

Local monthly household cell phone bills are normally distributed with a standard deviation of $11.

`\sigma = 11`

We are supposed to find the probability that a randomly selected monthly cell phone bill is less than $95 i.e.P(x<95)

`Z=(x-\mu)/(\sigma)`

`Z=(95-73)/(11)`

Z=2

Refer the z table for p value

So,p value = 0.9772

Hence the probability that a randomly selected monthly cell phone bill is less than $95 is 0.9772