Question

A brother and sister leave school at the same time, moving in opposite directions. If the brother walks away at a speed of 3.5 miles per hour, and the sister runs at a speed of 7.5 miles per hour, how far apart are they after half an hour

Answer 1

5.5 miles

Explanation:

The brother walks 3.5 miles in 1 hour. In half and hour, he walks half of 3.5 miles, or 1.75 miles.

The sister runs 7.5 miles in 1 hour. In half an hour, she runs half of 7.5 miles, or 3.75 miles.

Add the two distances:

1.75 miles + 3.75 miles = 5.5 miles