yamini.mv wrote:

hi bunnel,

in the first 2 hrs the fly travels 20 kms and at this point it reaches the man from Reston who has travelled 10 kms in this time.After this when it travels back along with the man from Reston,both men meet at another 5 kms.

So the fly has travelled 25 kms when it lands on the shoulder of the man from Kensington.

Where am i going wrong?

Pls reply

Hi..

Where you are going wrong is

Taking speed of fly also as 5km/h after it meets the other hikerSo the fly travels 20km and meets second hiker.

Then it turns back and moves with 10km/h to meet first hiker, and it will not meet him at 5km /h but they travel distance of 10km in combined speed of 10+5..... Time taken =10/15, so fly will travel 10*10/15 in this time..

And again turn back and move..

Best method is to find after how much time these hikers meet as nothing is hampering their move and then see how much that fly will travel in that time.

So distance 30 combined speed 5+5=10, so time taken =20/10=3h..

In 3h fly will travel 10*3=30

Ans

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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372

2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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