The time required for an automotive center to complete an oil change service on an automobile approximately follows a normaldistribution,with a mean of19minutes and a standard deviation of3minutes.

(a)The automotive center guarantees customers that the service will take no longer than20

minutes. If it does takelonger,the customer will receive the service forhalf-price.What percent of customers receive the service forhalf-price?

(b)If the automotive center does not want to give the discount to more than3%of itscustomers,how long should it make the guaranteed timelimit?

(a)The percent of customers that receive the service forhalf-priceis

Round to 2 decimal places as needed.