# Confidence Interval

A consulting firm which does consulting jobs on a cost per job basis wants to estimate its average pay per hour. The firm's manager takes a random sample of n=30 jobs and calculates the pay per an hour. The par per an hour values are listed below, rounded to the nearest dollar.

17 23 14 20 68 40 31 19 19 32 13 37 32 28 34

23 29 27 24 27 15 17 28 21 18 24 37 20 22 30

A. Determine a 90% confidence Interval for the mean pay per an hour,u?, of this firm's consulting jobs.

B. Interpet your results in word. (USE COMPLETE SETENCES, PLEASE and THANK YOU, SO MUCH)

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#### Solution Preview

A. Determine a 90% confidence Interval for the mean pay per an hour,u?, of this firm's consulting jobs.

<br>

<br>We calculate the sample mean M= 26.3

<br>N = 30, then degree of freedom = 30-1=29

<br>Standard Deviation = 10.655 (use "=STDEV" function in EXCEL)

<br>Standard Error = SD/SQRT(N) = 10.655/ SQRT(30) =1.945

<br>From ...

#### Solution Summary

A consulting firm which does consulting jobs on a cost per job basis wants to estimate its average pay per hour. The firm's manager takes a random sample of n=30 jobs and calculates the pay per an hour. The par per an hour values are listed below, rounded to the nearest dollar.

17 23 14 20 68 40 31 19 19 32 13 37 32 28 34

23 29 27 24 27 15 17 28 21 18 24 37 20 22 30

A. Determine a 90% confidence Interval for the mean pay per an hour,u?, of this firm's consulting jobs.

B. Interpet your results in word. (USE COMPLETE SETENCES, PLEASE and THANK YOU, SO MUCH)