Problem Solving

Boats in streams !, they can be very tricky at times!!!!

Okay, here is the basic theory behind it, there are 4 different speeds associated with these problems

1. Upstream Velocity -U
2. Downstream velocity - D
3. Speed of stream - S
4. Speed of boat in still water - B

Upstream velocity is the velocity at which a boat can travel upstream that is the difference between the velocity of the boat and speed of the stream

U= B-S -- (1)


Downstream velocity is the velocity at which a boat can travel downstream that is the sum of the velocity of the boat and speed of the stream

D= B+S --- (2)

(1) +(2) gives ,

2B= U+D
=>B= (U+D)/2

Similarly (2)-(1)
=> S = (D-U)/2

This is the only fundae you need to know while trying to solve a boat in stream problem

Question
A boat travels upstream at a speed of 4 mph and then downstream at a speed of 8 mph. What is the speed of the boat in still water and what is the speed of the stream?

Answer
When the downstream speed (D) and upstream (U) of a boat are given:
The speed of boat in still water, B = (D+U)/2 =6 Mph
Speed of the stream S = (D-U)/2 = 2 mph

That was easy , huh? , I am sure you will encounter more interesting problems once you look for it. If you have any problems with any of the Boat in stream problems feel free to post it here.

Happy learning
Ajith

Thanks Ajith, for the initiative

you are always welcome,

Please suggest me a topic for I am lazy!!!

" A boat travels 12 km upstream and back in 1 hour 45 minutes. If the speed of the current is 3km/hr throughout, find the speed of the boat in still water"

Please solve this to test your understanding, let me see who posts the answer first.


Statutory warning : This Problem may not be GMATish

cool job Ajith


but have you seen such problems in GMAT? or is it CAT hangover? (even if it is, its always welcome to check challenging problems ... so ignore this post )
sorry i've not checked GMAT PS lately...

Neo2000 what do you think?
is it CAT hangover?

I agree there a bit of CAT hangover here but, it is a problem worth trying isn't it?. I will edit the question post to reflect this view