Answer:
Joseph;
85.5 miles per hour.
Step-by-step explanation:
We need to put their speeds in the same unit.
Joe swam at the rate of 4.5 miles per hour.
Joseph swam at the rate of 1 1/2 of a mile per minute (1.5 miles per minute). Let us convert this to miles per hour.
To do that, multiply it by 60 minutes:
1.5 * 60 = 90 miles per hour
Joseph swam faster, because his speed is greater than Joe's speed.
The difference in their speeds is:
90 - 4.5 = 85.5 miles per hour
Joseph swam 85.5 miles per hour faster than Joe.
