Aptitude - Boats and Streams - Discussion
Discussion Forum : Boats and Streams - General Questions (Q.No. 6)
6.
A boat running downstream covers a distance of 16 km in 2 hours while for covering the same distance upstream, it takes 4 hours. What is the speed of the boat in still water?
Answer: Option
Explanation:
| Rate downstream = |  |
16 |  kmph = 8 kmph. |
| 2 |
| Rate upstream = | |
16 | kmph = 4 kmph. |
| 4 |
 Speed in still water = |
1 | (8 + 4) kmph = 6 kmph. |
| 2 |
Video Explanation: https://youtu.be/3D8uAfzz3l0
Discussion:
13 comments Page 1 of 2.
Rangaraj c said:
1 decade ago
Speed of downstream = 16/2 = 8.
Speed of upstream = 16/4 = 4.
Upstream speed u-v = 4.
Downstream speed u+v = 8.
u is the speed of still water and v is the speed of stream.
then by adding this,
u+v+u-v = 8+4.
2u =12.
u = 6 kmph.
Speed of upstream = 16/4 = 4.
Upstream speed u-v = 4.
Downstream speed u+v = 8.
u is the speed of still water and v is the speed of stream.
then by adding this,
u+v+u-v = 8+4.
2u =12.
u = 6 kmph.
(3)
Naresh said:
1 decade ago
Speed of downstream (d) = distance/time ==> 16/2 kmph ==> 8 kmph.
Speed of Upstream (u) = distance/time ==> 16/4 kmph ==> 4 kmph.
Speed of the boat in still water = 1/2 (d + u) ==> 1/2 (8 + 4) ==>6 kmph.
Speed of Upstream (u) = distance/time ==> 16/4 kmph ==> 4 kmph.
Speed of the boat in still water = 1/2 (d + u) ==> 1/2 (8 + 4) ==>6 kmph.
(1)
Riz said:
6 years ago
Simple explanation:
Downstream speed=16/2=8 km/hr=a.
Upstream speed=4 km/hr (mentioned in question) =b.
Speed of boat in still water=0.5 (a+b) =0.5 (8+4) =6 km/hr.
Downstream speed=16/2=8 km/hr=a.
Upstream speed=4 km/hr (mentioned in question) =b.
Speed of boat in still water=0.5 (a+b) =0.5 (8+4) =6 km/hr.
(1)
Nikul Rana said:
10 years ago
Speed downstream = X+Y = (16)/2 = 8kmph;
Speed upstream = X-Y = 16/4 = 4 kmph;
So we can say that, Speed pf the boat in still water = {(X+Y)+(X-Y)}*1/2 = 6 kmph.
Speed upstream = X-Y = 16/4 = 4 kmph;
So we can say that, Speed pf the boat in still water = {(X+Y)+(X-Y)}*1/2 = 6 kmph.
Tanuja said:
2 years ago
Speed at downstream = 16/2 = 8kmph
Speed at upstream = 16/4 = 4kmph
Speed at downstream + speed at upstream = x + y + x - y.
ie
8 + 4 = 2x
So x = 6kmph.
Speed at upstream = 16/4 = 4kmph
Speed at downstream + speed at upstream = x + y + x - y.
ie
8 + 4 = 2x
So x = 6kmph.
(3)
Mrithula said:
1 decade ago
Formula for finding the speed of the boat is
1/2(upstream speed+ downstream speed)
here upstream speed=8 and
downstream speed=4
1/2(upstream speed+ downstream speed)
here upstream speed=8 and
downstream speed=4
Brindha said:
1 decade ago
Downstream = 16/2 kmph = 8 kmph.
Upstream = 16/4 kmph = 4 kmph.
Still boat is = 8 + 4 = 12.
Half of the 12 is 6.
So 6 kmph.
Upstream = 16/4 kmph = 4 kmph.
Still boat is = 8 + 4 = 12.
Half of the 12 is 6.
So 6 kmph.
(3)
Divya said:
1 decade ago
Upwards 16/2hrs = 16/2 kmhr = 8.
Dowards 16/4hrs = 16/4 = 4.
Upwards + downwards/2 = 8+4/2 = 6.
Dowards 16/4hrs = 16/4 = 4.
Upwards + downwards/2 = 8+4/2 = 6.
(5)
Aishwarya said:
8 years ago
The speed in still water =1/2(upstream +downstream).
8 = upstream speed.
4 = downstream speed.
8 = upstream speed.
4 = downstream speed.
(1)
Shashi said:
1 decade ago
Why we are adding both and multiply by 1/2(8+4) ?
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