The sample of n = 9 individuals was selected from the normally distributed population with mean of µ = 25 and a standard deviation σ = 6. Treatment was administered to sample and, after treatment, nine individuals produced following scores:
36, 27, 30, 33, 22, 30, 30, 24, 38.

a. Compute the sample mean.

b. Draw histogram showing sample distribution

c. Does sample appear to be centered around µ = 25 or does treatment appear to have moved scores away from µ = 25?

d. Use hypothesis Test with α = .05 to find out whether treatment had significant effect.

e. Looking at sample distribution from part b, find out how big treatment effect is. Specifically, determine the distance between sample mean and original population mean?

f. Calculate Cohen's d to measure size of the treatment effect.