UPSC Maths Problems Challenge : A Problem A Day! (Day 22)

This is kind of a confusing question,I mean to say that I am sure of the way it is to be done but what I am not sure of is the meaning of the question.It is not very clear where the boat goes (that whether it goes towards or far from the shore) but since it says from and not back,I am considering it goes away from and not towards the shore.
This being my last Maths post this week,(I am writing it on a working day as I won't be able to on the weekends as I will be out of station.) I tried searching for authentic sources for verifying the correct answer but most of the solvers on the website I got the question from have got 3 km/hr as a solution.And I think this is an authentic way to solve the problem (as I have in this post).






Today's Problem(02/07/2015)


Question Credit : http://www.m4maths.com

A person goes by a boat 1km upstream to reach a point P where his hat falls into water after 
travelling 10 more minutes from p,he returns towards the shore and catches up with the hat exactly at the shore. what is the speed of the water current?

I am not studying Physics as a main subject right now but I can say that I loved the subject and studied about it day and night back in Class IX and X. (Class X preparation was more pragmatic,so the early months of Class IX does depict it.)I did not study it basically because it had very little relations,rather very insignificant relations with Economics as a subject (and NOT in practicality.)
I still do have a little part of Physics in Computer Application (which is my third subject) within concepts of Boolean Algebra but whenever I see a sum on Brilliant regarding Physics,I do not hesitate to give it a try.

Coming to the solution part of this problem,let the speed of the current and that of the boat be x km/hr. (Since the travel is only upstream,that is in the direction of the velocity of the water current.)
Now,total time taken = 1/2x + 1/2x = 2/2x = x hrs = 20 minutes = 20/60 hour = 1/3 hour
So,x = 3 km.


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