A marketing manager of a pizza parlor propose a campaign to promote online sales in a town during the time of lockdown. It is proposed that customers be compensated with RM7 e-Voucher if delivery time is greater than 20 minutes for addresses located within four kilometers radius from the parlor with minimum order of RM40. The manager collected delivery time of 30 orders out of the total of 180 orders in the month of January of 2021 and found that the delivery time has mean of 15 minutes. In the past, the standard deviation of delivery time for the delivery staff has been found 3 minutes.

a). What is the probability that delivery time within the town is less than 10 minutes?

b). What is the probability that delivery time is greater than 18 minutes?

c). Would you recommend the marketing manager to make the statement in the promotional flyers? Explain your answer.