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:
107 comments Page 1 of 11.
Anish said:
1 decade ago
How this required ratio? pls explain?
(1)
Pradeesh said:
1 decade ago
How can the y-x/2 become the current ratio?
Saranya said:
1 decade ago
Can you explain the process clearly?
Ashis said:
1 decade ago
As it is given to find out the ratio of speed of boat to speed of water w.r.to still water that is how required ratio is calculated.
You can find out from important formulae option i.e.
1/2(y-x)/1/2(y+x)
where y=speed at downstrem
x=speed at upstream.
You can find out from important formulae option i.e.
1/2(y-x)/1/2(y+x)
where y=speed at downstrem
x=speed at upstream.
Ravi said:
1 decade ago
I didn't understand how 8*4/5 will get.
Bharath said:
1 decade ago
Given is 8 hr 48min so converting min to hr
We have 48/60=4/5
We have 48/60=4/5
PHANI said:
1 decade ago
Thanks Ashis.
Anchal said:
1 decade ago
I am not able to understand the required ratio. ? how it is related with the speed of boat to speed of water. ?
Gita said:
1 decade ago
I'm not able understand the ratio?can you give brief explanation.
Binza said:
1 decade ago
Speed=distance/time
therefore distance=speed*time.
let consider speed at upstream is "x" and at downstream is "y", then distance covered (upstream in 8 hrs 48 min)= x*8*4/5
here 8hours and 48minutes=8*48/60=8*4/5
and distance covererd (downstream in 4hours=y*4
to relate both these equation
from question ,we know that distance covered are same
therefore x*8*4/5 = y*4
y=11/(5*x)
we know that speed are different in down stream and upstream.
if both are in same direction
take difference(x-y)
if they are in opposite
take sum(x+y)
required ratio =(x+y)/2 : (x-y)/2 // here 2 is to take average.
then answer is 8:3
therefore distance=speed*time.
let consider speed at upstream is "x" and at downstream is "y", then distance covered (upstream in 8 hrs 48 min)= x*8*4/5
here 8hours and 48minutes=8*48/60=8*4/5
and distance covererd (downstream in 4hours=y*4
to relate both these equation
from question ,we know that distance covered are same
therefore x*8*4/5 = y*4
y=11/(5*x)
we know that speed are different in down stream and upstream.
if both are in same direction
take difference(x-y)
if they are in opposite
take sum(x+y)
required ratio =(x+y)/2 : (x-y)/2 // here 2 is to take average.
then answer is 8:3
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