Question

In a simple random sample of 75 working adults in a city in Virginia, the average commute time for these workers was 23.65 minutes. The standard deviation from this sample was 18.50 minutes. A 95 percent confidence interval for the mean commute time for all adult workers in this city is approximately what?

Answer #1

We have given that,

Sample mean =23.65 minutes

Sample standard deviation =18.5 minutes

Sample size =75

Level of significance=1-0.95=0.05

Degree of freedom =74

t critical value is (by using t table)= 1.993

Confidence interval formula is

=(19.39,27.91)

Lower confidence limit= 19.39 minutes

Upper confidence limit= 27.91
minutes.

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