Aptitude - Boats and Streams - Discussion
Discussion Forum : Boats and Streams - General Questions (Q.No. 1)
1.
A boat can travel with a speed of 13 km/hr in still water. If the speed of the stream is 4 km/hr, find the time taken by the boat to go 68 km downstream.
Answer: Option
Explanation:
Speed downstream = (13 + 4) km/hr = 17 km/hr.
| Time taken to travel 68 km downstream = |  |
68 |  hrs = 4 hrs. |
| 17 |
Discussion:
46 comments Page 4 of 5.
Laxmidhar said:
10 years ago
Sp of down stream = (13+4) = 17.
Time taken = 68\17 = 4 hr.
Time taken = 68\17 = 4 hr.
Chetan said:
10 years ago
It means speed of boat in still water is 13 km/h.
Praveen said:
10 years ago
Still water means? How it has speed?
ROSHAN said:
10 years ago
Still water speed + Boat speed = Total speed (down stream).
Time = Distance/Speed.
Time = Distance/Speed.
V!cky said:
10 years ago
Use Speed = Distance /Time formula.
Still in water u+v = 13+4 = 17.
68/17 = 4 km/hr.
Still in water u+v = 13+4 = 17.
68/17 = 4 km/hr.
Prassanna.s said:
1 decade ago
Thanks for giving the correct answer.
Srikanth said:
1 decade ago
Downstream speed = a.
Upstream speed = b.
Stream speed = 1/2 (a-b)----Formula.
Boat speed = 1/2 (a+b)-----Formula.
Given boat speed = 13.
Stream speed = 4.
So 1/2(a+b)+1/2(a-b) = 13+4.
==> a=7.
Given D = 68km.
D = S*T.
Ta = D/Sa.
=>68/17.
=>4.
So time taken by the boat to go 68 km downstream is 4 hrs.
Upstream speed = b.
Stream speed = 1/2 (a-b)----Formula.
Boat speed = 1/2 (a+b)-----Formula.
Given boat speed = 13.
Stream speed = 4.
So 1/2(a+b)+1/2(a-b) = 13+4.
==> a=7.
Given D = 68km.
D = S*T.
Ta = D/Sa.
=>68/17.
=>4.
So time taken by the boat to go 68 km downstream is 4 hrs.
Somya said:
1 decade ago
It is given in the question to find time taken to go 68 km downstream.
Manikyam said:
1 decade ago
How to know particularly which formula to use whether downstream or upstream? Bit confusing?
WAngdeep Tamang said:
1 decade ago
Speed in Still water = 13 km/h.
Speed of the stream = 4 km/h.
Downstream = 13+4 = 17km (speed in Still water + speed of the stream).
Time Take = 68/17 = 4 hrs.
Speed of the stream = 4 km/h.
Downstream = 13+4 = 17km (speed in Still water + speed of the stream).
Time Take = 68/17 = 4 hrs.
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