If the average running speed of an amateur athlete (in miles per hour) after training for t days is given by S(t) = 0.31 Int + 11.9, then answer the following. ROUND YOUR FINAL ANSWERS TO 2 DECIMAL PLACES. A) Find the average running speed of amateur athletes that train for 91 days. B) How many days of training would yield an average speed of 13.8 miles per hour? miles per hour days