Sam left his school at 3: 05. he walked at a speed of 3.2 mph. 15 minutes later, al started running after him, and he caught up with sam 10 minutes later. what was al’s speed?

Total time taken by Sam before Al caught up with him = 15+10 = 25 minutes

In hours = 25 minutes = 25/60 = 5/12 hrs
Distance covered by Sam = Distance covered by Al = Speed (Sam) * time taken = 3.2*5/12 = 4/3 miles.

Al takes 10 minutes to cover that distance. Therefore,
Al's speed = Distance/time = (4/3)/(10/60) = (4/3)*(60/10) = 8 mph