Answer
The average speed of the winner in 1978 was $29.404$ miles per hour faster than the average speed of the winner in 2011.
Work Step by Step
Subtract the average speed in 2011 from the average speed in 1978
$= 159.73 - 130.326$
$= 29.404$ miles per hr
The average speed of the winner in 1978 was $29.404$ miles per hour faster than the average speed of the winner in 2011.