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 (in \$)? (Use at least 1,000 trials. Round your answer to two decimal places.) $ (b) What is the probability that Grear will refund more than $25 for a tire? (Use at least 1,000 trials. Round your answer to three decimal places.)