Question

Jane left the school and started to bike along the road at a rate of 12 mph. Her friend Sally left the school 10 minutes after Jane, biking on the same road at a rate of 15 mph. How long will it take Sally to catch up with Jane?

Answer 1

8 minutes if Jane was assumed to be stationary

Explanation:

The question is on relative speed

First find the distance covered by Jane when Sally left school

Speed=Distance/Time ⇒⇒ Distance=Time×Speed

Time=10minute=10/60 hrs

Jane's speed= 12mph

Distance covered by Jane when Sally left school was= 12 ×10/60 = 2miles

So, when Sally left school, Jane was 2 miles away. To find the time Sally requires to catch up with Jane;

Time=Distance/speed

Time of meeting =2/15 hrs ⇒⇒ 2/15 × 60 =8minutes