Data Sufficiency

Altogether walked from R to W for 12 hours. What is the average speed?
(1) First 8 hours were traveled at even speed of 56 mph
(2) Latter 8 hours traveled at avg speed of 56 mph

ern5231 wrote:Altogether walked from R to W for 12 hours. What is the average speed?
(1) First 8 hours were traveled at even speed of 56 mph
(2) Latter 8 hours traveled at avg speed of 56 mph

you missed something. plz correct the error and repost.

If even speed = constant speed, then the answer is (C)

From (A) we learn that first 4 hours the speed was 56mph, from (B) we learn that last 8 hours the avg. speed os 56mph. Hence 56mph is overall average speed.

Is this approach right? average speed = total distance / total time = 8 * 56 +8 * 56-4 * 56/12, choose c

how did you solve this?

In a Q, it says 12 hours, but each statement gives 8 hrs, totaling 16 hrs.

I am confused

yeah.. if Even speed == constant speed Ans is C.

We need to find out the total distanve covered in 12 hrs.
From A : if he is traveling at a constant speed for 8 hrs, he covers 56*4 miles in first four hrs.
From B: if the average speed in the last 8 hrs is 56 mph, then Distance traveled in 8hrs = 56*8

Combining both, we can find the avg speed = (56*4+56*8)/12


~V