A chocolate distributer claims that a new ad featuring picture of a well-known model will increase product sales by average of 155 boxes in a week. For a random sample of 16
supermarkets the average sales increase 160 boxes, and the standard deviation was 16 boxes.
Assuming that the population is normally distributed, test the company's claim at the 5%
significance level.
*Please explain the solution steps briefly (define hypothesis, one sided? Two sided? Critical
value, decision...)
*When you need to use the notation of population mean, you can write "mu”, similarly
“xbar”, “sigma”, “variance”,...​