Two Population Means with Unknown Standard Deviations · Try It 2
A study is done to determine if Company A retains its workers longer than Company B. Company A samples 15 workers, and their average time with the company is five years with a standard deviation of 1.2. Company B samples 20 workers, and their average time with the company is 4.5 years with a standard deviation of 0.8. The populations are normally distributed.
(a) Are the population standard deviations known?
(b) Conduct an appropriate hypothesis test. At the 5% significance level, what is your conclusion?
Its source prints no answer for this problem, so there's nothing to check against.
OpenStax, Introductory Statistics 2e · §10.1 Two Population Means with Unknown Standard Deviations · Try It 2
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