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.
This time we are giving you the shortcuts of boat and streams questions.
Remember the trick, 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
This article is originally published by ExamFormIndia.in.