Bunuel wrote:
A bus traveled from its depot to its destination at an average speed of 60 kilometers per hour. On its return to the depot along the same route, the bus traveled at an average speed of only 40 kilometers per hour, making the trip 4 hours longer. What is the total distance of the round trip?
A. 360 kilometers
B. 400 kilometers
C. 600 kilometers
D. 800 kilometers
E. 960 kilometers
Kudos for a correct solution.
Two ways to solve this qn: (Maybe many ways)
1. Distance traveled is same in to and fro problems
60 * t = 40 * (t + 4) => Solving for t, t = 8
Distance = 8*60 = 480 (Usually this will be the trap answer). But they have asked for round trip distance. hence 2*D = 960.
Option E
2. Time Difference btw the two trips is 4 hours. This difference is bec of difference in speed.
Hence,
T2 - T1 =4
D/40 - D/60 = 4
Solving for D, D=> 480; 2D => 960.
Option E
Would like to know if there are any standard techniques that can be applied to all Time/Distance/Speed problems.
Thanks