Face mask selling price. In March 2020 and early April 2020, the highest number of COVID-19 cases were reported in Southeast Asia. This caused face masks and “survival kits” to be sold out in local stores, and shoppers raced to online retailers to buy face masks, hand sanitizers, hazmat suits, and other items to protect against the coronavirus. The New Straits Times published an article on March 21, 2020, reporting that the Government of Malaysia government had fixed new selling prices for face masks to ensure that there is enough supply during the ongoing two week-long Movement Control Order (MCO) aimed at halting the spread of COVID-19 in the country. The selling price for a 2-ply face mask had an average of RM10 per box with a standard deviation of RM2 per box. The government examined a sample of 200 retail outlets’ mask selling prices to determine whether they had followed the rule.

a. What is the probability that the selling price for a 2-ply face mask in the sample is greater than RM10.50?

b. Suppose it was reported that x = RM9. Use this information to make an inference about the true mean m selling price per box for the 2-ply face mask.