Aptitude - Boats and Streams - Discussion
Discussion Forum : Boats and Streams - General Questions (Q.No. 3)
3.
A boat running upstream takes 8 hours 48 minutes to cover a certain distance, while it takes 4 hours to cover the same distance running downstream. What is the ratio between the speed of the boat and speed of the water current respectively?
Answer: Option
Explanation:
Let the man's rate upstream be x kmph and that downstream be y kmph.
Then, distance covered upstream in 8 hrs 48 min = Distance covered downstream in 4 hrs.
 |
 |
x x 8 | 4 |  |
= (y x 4) |
| 5 |
| |
44 | x =4y |
| 5 |
| y = |
11 | x. |
| 5 |
 Required ratio = |
|
y + x | |
: | |
y - x | |
| 2 | 2 |
| = | |
16x | x | 1 | |
: | |
6x | x | 1 | |
| 5 | 2 | 5 | 2 |
| = | 8 | : | 3 |
| 5 | 5 |
= 8 : 3.
Discussion:
109 comments Page 3 of 11.
Raj D said:
5 years ago
Thanks @Ajit.
Anusha said:
5 years ago
Thanks @Ajit.
Ajit said:
5 years ago
Just look simple method:
Upward= 8 hr + 48 Min. = 8+48/60 = 44/5.
Downward = 4 hr.
Speed of stream = (44/5 -4)/2 = 2.4 hr.
Speed of boat = 4+2.4 = 6.4 hr.
So, Ratio is 6.4:2.4.
i.e 8:3.
Upward= 8 hr + 48 Min. = 8+48/60 = 44/5.
Downward = 4 hr.
Speed of stream = (44/5 -4)/2 = 2.4 hr.
Speed of boat = 4+2.4 = 6.4 hr.
So, Ratio is 6.4:2.4.
i.e 8:3.
(6)
Chetan Shahi said:
5 years ago
Given data,
Upstream time=8 hr 48 min=8x48/60hr=44/5 hr....(1).
Downstream time =4 hr......(2).
The distance is the same.
According to (1) case:
Distance =upstream speed x upstram time.
Distance =(u-v)x44/5=44/5u-44/5v.......(3)
According to (2) case:
Distance =downstream speedxdownstream time
Distance =(u+v)x4=4u+4v........(4)
As distance traveled is equal ,
So (3) =(4).
44/5u-44/5v=4u+4v.
44/5u-4u=4v+44/5v.
24/5u=64/5v.
u/v=8/3.
Upstream time=8 hr 48 min=8x48/60hr=44/5 hr....(1).
Downstream time =4 hr......(2).
The distance is the same.
According to (1) case:
Distance =upstream speed x upstram time.
Distance =(u-v)x44/5=44/5u-44/5v.......(3)
According to (2) case:
Distance =downstream speedxdownstream time
Distance =(u+v)x4=4u+4v........(4)
As distance traveled is equal ,
So (3) =(4).
44/5u-44/5v=4u+4v.
44/5u-4u=4v+44/5v.
24/5u=64/5v.
u/v=8/3.
Sucharitha said:
5 years ago
8+4/5:4.
44:20.
Speed of the boat=64.
Water speed=24.
64:24.
8:3.
44:20.
Speed of the boat=64.
Water speed=24.
64:24.
8:3.
(1)
Soumyarahul said:
6 years ago
First, convert the hours into a minute.
528 mints &240mts.
while simplifying the above minutes,
we get,
11 and 5.
11+5/2 :11-5/2.
8:3.
528 mints &240mts.
while simplifying the above minutes,
we get,
11 and 5.
11+5/2 :11-5/2.
8:3.
(1)
Farru_faiz said:
6 years ago
If distance is equal thn formula
downstream X time 1 = upstream X time 2
downstream = U+V/2
upstream = U-V/2
downstream = speed of boat
upstream = speed of stream
i.e, U+V/2 * time 1 = U-V/2 * time 2
Now substitute the values in the above formula
downstream X time 1 = upstream X time 2
downstream = U+V/2
upstream = U-V/2
downstream = speed of boat
upstream = speed of stream
i.e, U+V/2 * time 1 = U-V/2 * time 2
Now substitute the values in the above formula
Vatshayan said:
6 years ago
An easy way to solve.
Let the speed of boat and water be x km/hr and y km/hr respectively.
Upstream = x-y km/hr.
Downstream = x+y km/hr.
[8+(48/60)](x-y) = 4(x+y)(SINCE DISTANCE IS EQUAL).
8+4/5(x-y) = 4x + 4y.
44/5 x - 44/5 y= 4x + 4y.
44/5x - 4x = 4y + 44/5 y.
24x = 64 y.
x/y = 64/24.
x/y = 16 / 6.
x/y = 8/3 (answer).
Let the speed of boat and water be x km/hr and y km/hr respectively.
Upstream = x-y km/hr.
Downstream = x+y km/hr.
[8+(48/60)](x-y) = 4(x+y)(SINCE DISTANCE IS EQUAL).
8+4/5(x-y) = 4x + 4y.
44/5 x - 44/5 y= 4x + 4y.
44/5x - 4x = 4y + 44/5 y.
24x = 64 y.
x/y = 64/24.
x/y = 16 / 6.
x/y = 8/3 (answer).
Shifali said:
6 years ago
Let the speed of the boat is u and that of the stream is v.
Time for upstream (u-v) is 528min and time took for downstream (u+v) is 240 min.
Distance covered is the same.
Since, D1=t1*(u-v) and d2= t2*(u+v).
And, d1=d2
So, t1*(u-v) = t2*(u+v).
(U-v)*528 = (u+v)*240
=> u/v = 8/3;
That is 8:3.
Time for upstream (u-v) is 528min and time took for downstream (u+v) is 240 min.
Distance covered is the same.
Since, D1=t1*(u-v) and d2= t2*(u+v).
And, d1=d2
So, t1*(u-v) = t2*(u+v).
(U-v)*528 = (u+v)*240
=> u/v = 8/3;
That is 8:3.
Reshi said:
6 years ago
Thanks @Bindu.
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