Question

A telecommunications company commissioned a study to investigate the amount of time that people spend on phone calls. The study that found that the length of time that people spend on a phone call is approximately normally distributed with a mean of 519 seconds and a standard deviation of 104.7 seconds. Calculate the standardized value (z) for a time of 630 seconds. Give your answer to 2 decimal places

Answer 1

`z = 1.06`

Explanation:

Given

`\bar x = 519` -- Mean

`\sigma = 104.7` --- Standard Deviation

`x = 630` --- Time

Required

Determine the standardized value (z)

The standardized value (z) is calculated using:

`z = (x - \bar x)/(\sigma)`

This gives:

`z = (630 - 519)/(104.7)`

`z = (111)/(104.7)`

`z = 1.06017191977`

`z = 1.06` --- approximated