3600 = 3600(60 + x) 60 + x The function s(x) = gives a person's average speed in miles per hour if he or she travels one mile in 60 + x seconds. Use a linear approximation to s at 0 to find a person's approximate average speed if he or she travels one mile in 50 seconds. What is his or her exact speed? mi The person's approximate average speed is 70 hr mi The person's exact speed is hr (Round to the nearest hundredth as needed.)