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Boat and Stream Problems shortcuts-Formulas with examples solved-how to solve quickly

Boat and Stream questions are asked in many competitive exams including SSC IBPS etc. this type of questions uses  Time and Distance Formulas to some level. So you need to be familiar with time and distance formulas first.

Learn time and distance formulas shortcuts with examples here.
 This time we are giving you the shortcuts of boat and streams questions.
The basic question is
how to solve boat and stream questions quickly
so here is the solution
remember the methods and formulas given below and you will be able to solve the boat and stream question as quickly as possible.

Below are some basic terms of boat and stream questions:
Downstream: if a boat or person travels the distance with the flow of the stream, then that speed is called downstream.
Upstream: if a boat or person travels the distance against the flow of the stream, then it is called upstream.
Now

If speed of boat is x km/h and speed of stream is y km/h , then
Boat speed in downstream = x+y  km/h   (both speed are added)
Boat speed in upstream = x-y   km/h        (y is subtracted from x because boat speed is in opposite direction to speed of stream)


If the speed of boat is x km/h in downstream and y km/h in upstream, then
 speed of boat in still water is =(x+y)/2
speed of stream = (x-y)/2


if the speed of boat or person  in still water is x and speed of stream is y and the boat has to cover a distance d km then
time taken in downstream T1 = d/(x+y)             ( because time = distance / speed )
time taken in upstream T2 = d/(x-y)
total time taken in going downstream and upstream T = T1+T2 = [d/(x+y)]+[d/(x-y)]

next formula
The speed of boat or person in still water is x and speed of stream is y then time taken in going upstream and downstream is given as A:B , then
A:B= (x-y)/(x+y)


Example :
The speed of a boat in still water is 6 km/h and speed of stream is 1 km/h. how much time will be taken by the boat in going 35 km first upstream and then downstream ?
Solution:
Putting the formula as discussed above:
T= [d/(x+y)]+[d/(x-y)] = [35/(6+1)] +[35/(6-1)] = 5+7 = 12 hours

Example 2:
A boat travels 18 km upstream in 5 hours and takes the same time in travelling 32 km downstream. Determine the speed of the stream?
Solution:
Speed of stream = ½) (speed in downstream- speed in upstream)= (½)[(32/5)-(18/5)] = (½)(14/5) = 1.4 km/h          
By using formula  speed = distance / time







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