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:
111 comments Page 6 of 12.
Hema said:
1 decade ago
I'm not understand this step 16/5*1/2 please help me.
Ashwini said:
1 decade ago
@Nitin Gusain.
Thanks yaar. It's so simple calculation.
But X-Y = -2 (Stream speed) So instead of that,
Y-X = +2 (Stream speed).
Thanks yaar. It's so simple calculation.
But X-Y = -2 (Stream speed) So instead of that,
Y-X = +2 (Stream speed).
Maneesh said:
1 decade ago
Simply equal the speeds in downstream and upstream we get the ratio,
upstream:downstream.
(x+y)/2 = (x-y)/2
(x+y) = (x-y)
Given upstream and downstream speeds,
Means x(44/5)=y(4).
y = x(11/5)
(x+Y) = (x-Y)
16x/5 = 6x/5
8:3 answer
upstream:downstream.
(x+y)/2 = (x-y)/2
(x+y) = (x-y)
Given upstream and downstream speeds,
Means x(44/5)=y(4).
y = x(11/5)
(x+Y) = (x-Y)
16x/5 = 6x/5
8:3 answer
Sandeep said:
1 decade ago
x/y = 5/11.
So, x=5 , y=11.
(x+y)/2 : (x-y)/2.
(11+5)/2 : (11-5)/2.
16/2 : 6/2.
8:3 answer.
So, x=5 , y=11.
(x+y)/2 : (x-y)/2.
(11+5)/2 : (11-5)/2.
16/2 : 6/2.
8:3 answer.
Raju said:
1 decade ago
I want to know how these equation is done?
16x/5 and 6x/5.
16x/5 and 6x/5.
Papesh roul said:
1 decade ago
Let the speed of the Boat be: a kmph and Speed of the stream be: b kmph.
Distance =44/5 * (a-b) = 4 * (a+b).
By this equation we will get a/b = 8:3.
Distance =44/5 * (a-b) = 4 * (a+b).
By this equation we will get a/b = 8:3.
SUJISHNU ADHYA said:
1 decade ago
An easy way to solve.
Let speed of boat and water be x km/hr and y km/hr respectively.
Upstream = x-y km/hr.
Downstream = x+y km/hr.
ATQ,
[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 speed of boat and water be x km/hr and y km/hr respectively.
Upstream = x-y km/hr.
Downstream = x+y km/hr.
ATQ,
[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).
Aparna said:
1 decade ago
We all know this basic rule of finding ratio which is:
x/y = a/b.
Further when we solve this, we get:
x+y/x-y = a+b/a-b .... equation (1).
Solution:
Let the boat's speed upstream be x & downstream be y.
Therefore,
According to the formula, Distance = Speed*Time.
We get for upstream, D= x*44/5.
& for downstream, D= x*4.
Now, in the question, it is given that the distance covered is same while going upstream and downstream.
Therefore,
x*44/5 = 4y.
x/y = 11/5 (satisfies the equation: x/y = a/b).
Now put this value of x/y in equation (1).
x+y/x-y = 11+5/11-5.
x+y/x-y = 16/6.
x+y/x-y = 8/3.
8:3 is the Answer.
x/y = a/b.
Further when we solve this, we get:
x+y/x-y = a+b/a-b .... equation (1).
Solution:
Let the boat's speed upstream be x & downstream be y.
Therefore,
According to the formula, Distance = Speed*Time.
We get for upstream, D= x*44/5.
& for downstream, D= x*4.
Now, in the question, it is given that the distance covered is same while going upstream and downstream.
Therefore,
x*44/5 = 4y.
x/y = 11/5 (satisfies the equation: x/y = a/b).
Now put this value of x/y in equation (1).
x+y/x-y = 11+5/11-5.
x+y/x-y = 16/6.
x+y/x-y = 8/3.
8:3 is the Answer.
Mady said:
1 decade ago
Boat Speed In still water = u.
Stream Speed = v.
DS = u+v US = u-v.
Distance = (u+v)4 = (u-v)44/5 (rough : 8*48/60= 44/5).
so (u+v) = (u-v)11/5 (rough : canceled 4 & 44.. 11 times).
5(u+v) = (u-v)11.
5u+5v = 11u-11v.
5u-11u = -11v-5v.
-6u = -16v.
u/v = 16/6= 8/3 .
So 8:3.
Stream Speed = v.
DS = u+v US = u-v.
Distance = (u+v)4 = (u-v)44/5 (rough : 8*48/60= 44/5).
so (u+v) = (u-v)11/5 (rough : canceled 4 & 44.. 11 times).
5(u+v) = (u-v)11.
5u+5v = 11u-11v.
5u-11u = -11v-5v.
-6u = -16v.
u/v = 16/6= 8/3 .
So 8:3.
Jessie said:
1 decade ago
How does the upstream:downstream relates the ratio speed of the boat:speed of the water current as asked in question?
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