Question

To estimate with a 99% confidence interval, the difference in mean earned income among men and women based on a sample of 30 women and 20 men, would you use for the significance test or confidence interval the t-student or the Z-score values? Why?

Answer 1

In the above problem we use t test for two means.

For z test we have two criterias..

1. the sample size is sufficiently large.

That is sample size greater than or equal to 30

2. The population standard deviations is known.

In the above nothing is mentioned about population standard deviations.

Therefore, we can't go with z test.

For above problem, we can make decisions usingt t test for two sample means.

We can find confidence interval using t test for two means.

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