The funciton s(x) = 3600 / (60 + x) = 3600 (60 + x)-1 gives a person's average speed in miles per hour if he travels one mile in x seconds more or less than 60 seconds. Use a linear approximation to s at 0 to find a person's approximate average speed if he travel one mile in 68 seconds.
a) What is the person's approximate average speed?
b) What is the person exact speed ?