The standard deviation of the population of individual scores is 15. A random sample of 40 ...

The standard deviation of the population of individual scores is 15. A
  random sample of 40 subjects yields a mean of 105.
 
  a. Calculate the standard error of the mean.
  b. Test the hypothesis, via the z test, that this sample could be
   representative of a population whose mean is known to be 100.

Question 2

A significant _____ is not as important as a significant _____.
 
  a. interaction; main effect
  b. main effect; interaction
  c. main effect of factor 1; main effect of factor 2
  d. All effects are equally significant.

Question 3

The fact that the two groups differed significantly regarding whether or
  not they had the meat cuts, means that
 
  a. Ho was accepted
  b. Ho was never tested
  c. Ho was rejected
  d. the dependent variable was not affected