gmatdriller wrote:Jerry travels 8 miles at an average speed of 40 miles per hour, stops for 10 minutes, and then travels another 20 mile at an average speed of 60 miles per hour. What is the total average speed at which Jerry traveled?
A: 40 mph B: 42.5 mph C: 44 mph D: 50 mph E: 52.5 mph

I only need clarifications on whether there is need to include the 10 minutes stoppage or not.

Thanks.
OA A

Jerry travels 8 miles at an average speed of 40 miles per hour...

So D = 8 , S = 40

Hence T = 1/5 hr

He then stops for 10 min = 1/6 Hr


Then travels another 20 mile at an average speed of 60 miles per hour.

D = 20 , S = 60

T = 20/60 => 1/3Hr

Hence Total Time taken is -

1/5 + 1/6 + 1/3 => 42/60 = 7/10 Hr..

Distance covered is 20 + 8 = 28 Miles...

Hence Avg speed = 28/(7/10) => 28*10/7 =>40 Miles/hr..

I thought it was a mistake, but bow it is clearer.

my regards.