# Standard deviation

An employer wants to set a time limit so that 90% of the employees will finish a job on time. Past history has shown that the time required to do the job is normally distributed and has a mean time of 32 minutes with a standard deviation of 6 minutes. How much time should the employer allow employees to finish the job? (Round up to the nearest minute.)

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#### Solution Preview

The z value for 90% is: 1.2816

Using the z formula:

z = (x-mean)/standard ...

#### Solution Summary

Step by step solution to the problem is provided.

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