The owners of Spiffy Lube want to offer their customers a 10-minute guarantee on their standard oil change service. If the oil change takes longer than 10 minutes to complete, the customer is given a coupon for a free oil change on the next visit. Based on the past history, the owners believe that the time required to complete an oil change has a normal distribution with a mean of 8.6 minutes and a standard deviation of 1.2 minutes. i. What percentage of customers will receive a free oil change coupon? ii. What percentage of customers have an oil change in less than 7.6 minutes? iii. What percentage of customers have an oil change in more than 9.6 minutes? iv. If management wants to limit the percentage of customers receiving a coupon to no more than one (1) out of every 25 customers on average, what should they change the guaranteed time to?