ENIGMA05 - Editorial

ad-hoc
editorial
engm2015
simple

#1

PROBLEM LINK:

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Author and Editorialist : Dhruv Mahajan

DIFFICULTY

Simple

EXPLANATION:

Average Speed is Not (u+v)/2.

But it is (total distance covered)/(total time taken).

Let distance from A to B is ‘d’, then time taken from A to B is d/u.
And distance between B to A will also remain ‘d’, hence time taken from B to A is d/v.

Total distance covered in the journey is 2d.
Hence average speed will be (total distance covered)/(total time taken),
which is (2d)/(d/u+d/v) which is equal to 2uv/(u+v).

Remember if u=0 and v=0 then avg speed will also be zero.

SOLUTIONS

Link to Solution


#2

Why was this contest not listed in the Contests section?


#3

It was a Closed Contest.