Which speed is the fastest? A: 4 miles in 1/3
B: 1/3 mile in 4 hours
C: 1/2 mile in 3 hours
D: 2 miles in 1 hour

1/3 of an hour is 20 minutes so 20 divided by 4 is 5 minutes per 1 mile.

1/3 of a mile is 4 hours so a full mile would be 3 times 4 which is 12 so every 12 hours is 1 mile.

1/2 a mile takes 3 hours and 2 times 3 is 6 so every 6 hours is 1 mile.

A. 5 minutes per mile

B. 12 hours per mile

C. 6 hours per mile

The correct choice is A.
I hope this helped you