A swimmer is in the pool swimming a race and covers a distance of d=2.2t+7 where t is the total time traveled in seconds, and d is the distance in meters. What is the average velocity of the swimmer between 1 and 20 seconds?
a) 9.5 m/s
b) 10.2 m/s
c) 11.7 m/s
d) 13.4 m/s