mgmt question...rate problem

[nqhussain]

Peter leaves Riverdale at 10:00 a.m. and starts pedaling his bicycle at 10 mph. If John starts on the same path at 2:00 p.m., when will he catch Peter if he pedals at 15 mph?
6:00 p.m.
6:30 p.m.
8:00 p.m.
8:30 p.m.
10:00 p.m.


please help. thanks

[mmukher]

John leaves 4 hours after Peter. Also John's 'net speed' is 15mph - 10 mph = 5 mph.

In 4 hours, Peter must have traveled, 10 * 4 = 40 miles.
After 4 hours John starts with his net speed of 5 mph. So the question is how long does it take for John to cover 40 miles at 5mph. Its 8 hrs.
So the ans should be 8 hrs from 2pm, 10pm.

[mmukher]

Also check out this post. This should clear out some concepts.

https://www.beatthegmat.com/og-rates-119-t9129.html

[kandyhot27]

Assume 'X' is the time after Peter left when they meet

Name / Speed / Time
Peter / 10 / x
John / 15 / x - 4 (because John started 4 hours after Peter did, hence his travel time would be 4 hours less)


10x = 15 (x-4) Because the distance traveled by both is same

Solve it and voila !
x = 12 hours

Hence the time they meet is 10 pm