A bee started flying from the front of a train with a speed of 69 km/hr towards another train, which is coming on the same track, towards the first train. Once it reaches the second train, it again flies back to the first train. Now when it reaches the first train, it again flies towards the second train. It keeps on flying between the trains till they collide. How much total distance, the bee will cover if the speed of the first and second train is 50 km/hr and 70km/ hr successively and the distance between them is 100 km, when the bee started flying.
75 km
90 km
57.5 km
Cannot be determined
None of the Above
Answer :Cannot be Determined
Solution (Fast Approach)
As the bee starts from the slower train and reaches the other train. It cannot fly back, as the speed of the second train is more than the bee.
Following can be Options:
Bee may get stuck with second train and then reaches the first train
Bee may be flying above the trains.
The whole concept here is, Bee cannot continue flying as the second train is moving with more speed.
As there is more than one option, answer should be "Cannot Be Determined"
Note: In the standard question the speed of bee is normally given more than both the Trains.
Solution for bee moving with more speed as compared to both the trains.
Total time taken by the trains to hit each other: 100/120 hr = (100*60)/120 = 50 min.
If speed of bee is say X km/hr, then total distance travelled by bee is X * 50/60 km, where X > 70
Imp: Lot of students solve a problem in traditional way. Many of the students who had solved this type of math problem, may have arrived at the answer 57.5 km. The basic reason for tweaking the question is to let people understand: If pattern changes in any competitive exam many students fall apart.
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