Please provide an explanation and step by step process on how these answers are chosen.
In an article appearing in Today's Health a writer states that the average number of calories in a serving of popcorn is 75. To determine if the average number of calories in a serving of popcorn is different from 75, a nutritionist selected a random sample of 20 servings of popcorn and computed the sample mean number of calories per serving to be 78 with a sample standard deviation of 7.
State the null and alternative hypotheses.
A. H0:  = 75, H1:  ≠ 75
B. H0:  ≤ 75, H1:  > 75
C. H0:  ≥ 75, H1:  < 75
D. H0:  = 75, H1:  > 75
Compute the z or t value of the sample test statistic.
A. z = 1.916
B. t = -1.916
C. t = 1.916
D. z = 1.645
At the  = .05 level of significance, does the nutritionist have enough evidence to reject the writer's claim?
C. Cannot determine
The solution provides step by step method for the calculation of Z test statistic for mean . Formula for the calculation and Interpretations of the results are also included.