To promote the new tire, Grear has offered to refund some money if the tire fails to reach 30,000 miles before the tire needs to be replaced. Specifically, for tires with a lifetime below 30,000 miles, Grear will refund a customer $1 per 100 miles short of 30,000.

a)For each tire sold, what is the average cost of the promotion?Round your answer to two decimal places.$(b)What is the probability that Grear will refund more than $25 for a tire?Round your answer to a one decimal percentage place.%