Aptitude - Boats and Streams - Discussion
Discussion Forum : Boats and Streams - General Questions (Q.No. 11)
11.
A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take to go 5 km in stationary water?
Answer: Option
Explanation:
| Rate downstream = |  |
1 | x 60 |  km/hr = 6 km/hr. |
| 10 |
Rate upstream = 2 km/hr.
| Speed in still water = | 1 | (6 + 2) km/hr = 4 km/hr. |
| 2 |
 Required time = |
|
5 | hrs = 1 |
1 | hrs = 1 hr 15 min. |
| 4 | 4 |
Discussion:
27 comments Page 3 of 3.
Thomas said:
6 years ago
I also agree, The answer should be 1h and 25 mins.
(3)
Ibrana said:
6 years ago
Please discuss the proper way to find required time.
Varshith said:
6 years ago
Thanks @Mayur.
Kessy said:
5 years ago
Anyone, please explain this step 1/2 times (6 + 2).
ABI said:
5 years ago
@Kessy
Simply need to find the speed of the boat.
You have downstream and upstream speed and,
Downstream speed=Speed of boat +Speed of stream.
6=x+y---------> 1
Upstream speed=Speed of boat-Speed of stream
4=x-y------------> 2
Solve both 1&2 equations and get x that is the speed of the boat.
Simply need to find the speed of the boat.
You have downstream and upstream speed and,
Downstream speed=Speed of boat +Speed of stream.
6=x+y---------> 1
Upstream speed=Speed of boat-Speed of stream
4=x-y------------> 2
Solve both 1&2 equations and get x that is the speed of the boat.
(2)
Anandh said:
3 years ago
@All.
It's very simple.
Speed of the downstream S = D/T.
D= 1km,
T = 10mint, mint convert to hour.
10/60 hour then,
S = 1km / (10/60)hr,
= 60/10 km/hr.
Downstream speed s = 6 km/hr then,
Upstream speed S = D/T.
= 2km / 1hr = 2km / hr.
Speed in still water = 1/2 ( Down S + Up S )
1/2 ( 6+2 ) = 4km / hr.
So we need T? For stationary water, D is given 5km ...
Then Speed in still water = 4km /hr.
T = D / S = 5/ 4
= 1 1/4 hours.
= 1hr 15 mint.
It's very simple.
Speed of the downstream S = D/T.
D= 1km,
T = 10mint, mint convert to hour.
10/60 hour then,
S = 1km / (10/60)hr,
= 60/10 km/hr.
Downstream speed s = 6 km/hr then,
Upstream speed S = D/T.
= 2km / 1hr = 2km / hr.
Speed in still water = 1/2 ( Down S + Up S )
1/2 ( 6+2 ) = 4km / hr.
So we need T? For stationary water, D is given 5km ...
Then Speed in still water = 4km /hr.
T = D / S = 5/ 4
= 1 1/4 hours.
= 1hr 15 mint.
(16)
Hasi said:
5 months ago
I agree that the answer will be 1 hour 25 min.
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