Aptitude - Boats and Streams - Discussion
Discussion Forum : Boats and Streams - General Questions (Q.No. 4)
4.
A motorboat, whose speed in 15 km/hr in still water goes 30 km downstream and comes back in a total of 4 hours 30 minutes. The speed of the stream (in km/hr) is:
Answer: Option
Explanation:
Let the speed of the stream be x km/hr. Then,
Speed downstream = (15 + x) km/hr,
Speed upstream = (15 - x) km/hr.
 |
30 | + | 30 | = 4 | 1 |
| (15 + x) | (15 - x) | 2 |
 |
900 | = | 9 |
| 225 - x2 | 2 |
9x2 = 225
x2 = 25
x = 5 km/hr.
Video Explanation: https://youtu.be/lMFnNB3YQOo
Discussion:
63 comments Page 7 of 7.
John said:
1 decade ago
What happen to the 900 and the 2?
Sagar said:
1 decade ago
In a stream running at 2km/h, a motor boat goes 10 km upstream and back again to the starting point in 55 minutes. Find the speed of the motorboat in still water? Please answer.
Lakki said:
10 years ago
Any shortcut method for this sum?
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