In: Statistics and Probability
A program was created to randomly choose customers at a shoe
store to receive a discount. The program claims 15% of the receipts
will get a discount in the long run. The manager of the shoe store
is skeptical and believes the program's calculations are incorrect.
She selects a random sample and finds that 12% received the
discount. The confidence interval is 0.12 ± 0.05 with all
conditions for inference met.
Part A: Using the given confidence interval, is it
statistically evident that the program is not working?
Explain.
Part B: Is it statistically evident from the
confidence interval that the program creates the discount with a
0.15 probability? Explain.
Part C: Another random sample of receipts is
taken. This sample is six times the size of the original. Twelve
percent of the receipts in the second sample received the discount.
What is the value of margin of error based on the second sample
with the same confidence level as the original interval?
Part D: Using the margin of error from the second
sample in part C, is the program working as planned? Explain.