The null and alternate hypotheses are:

Question

H0: μ1 = μ2
H1: μ1 ≠ μ2

A random sample of 15 items from the first population showed a mean of 50 and a standard deviation of 5. A sample of 12 items for the second population showed a mean of 46 and a standard deviation of 15. Assume the sample populations do not have equal standard deviations.

Answer 1

Do you understand the difference between a sample and a population?

Z = (mean1 - mean2)/standard error (SE) of difference between means

SEdiff = √(SEmean1^2 + SEmean2^2)

SEm = SD/√n

If only one SD is provided, you can use just that to determine SEdiff.

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z score and compare it to whatever level of significance you are using.