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 4 of 11.
Gokul chandra upadhyay said:
9 years ago
Let x = speed of boat.
y = speed of stream.
t1= upstream time & t2 = downstrem time.
formula : x/y = (t1 + t2)/(t1 - t2).
{t1 = 8h 48m = 44/5h, t2 = 4h}
so, x/y = (44/5 + 4)/(44/5 - 4).
x/y = (44 + 20)/(44 - 20) = 64/24 = 8/3.
x:y = 8:3.
y = speed of stream.
t1= upstream time & t2 = downstrem time.
formula : x/y = (t1 + t2)/(t1 - t2).
{t1 = 8h 48m = 44/5h, t2 = 4h}
so, x/y = (44/5 + 4)/(44/5 - 4).
x/y = (44 + 20)/(44 - 20) = 64/24 = 8/3.
x:y = 8:3.
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
Ranjith said:
9 years ago
Let me explain.
Ratio between the speed of the boat and speed of the water current is :
Average speed of upstream and downstream to the water current speed (downstream - upward stream velocity we get average water moving velocity).
Ratio between the speed of the boat and speed of the water current is :
Average speed of upstream and downstream to the water current speed (downstream - upward stream velocity we get average water moving velocity).
Vaishnavi said:
5 years ago
Upstream, x = b(speed of boat) - w(speed of water).
Downstream, y = b + w.
Equalling both using distance.
(b+w) *44/5 = (b-w) * 4.
(b+w)*11/5 = (b-w),
11b+11w = 5b-5w.
6b = -16w(ignore negative sign).
b/w = 8/3.
So, b : w = 8 : 3.
Downstream, y = b + w.
Equalling both using distance.
(b+w) *44/5 = (b-w) * 4.
(b+w)*11/5 = (b-w),
11b+11w = 5b-5w.
6b = -16w(ignore negative sign).
b/w = 8/3.
So, b : w = 8 : 3.
Ronie said:
7 years ago
First convert Hours to Mins.
8hrs 48mins= 528mins & 4hrs= 240mins.
Speed Down =x/528,
Speed Up=x/240,
Speed of stream =(x/240-x/528)÷2=x/880,
Speed of boat= x/240-x/880 =x/330,
Ratio=(x/330)/(x/880)= 8:3.
8hrs 48mins= 528mins & 4hrs= 240mins.
Speed Down =x/528,
Speed Up=x/240,
Speed of stream =(x/240-x/528)÷2=x/880,
Speed of boat= x/240-x/880 =x/330,
Ratio=(x/330)/(x/880)= 8:3.
Mahesh said:
4 years ago
When the same distance is mentioned in this type of question best shortcut is the sum:difference. Nothing but 12hr 48 min: 4hr 48min.
Other than change completely minutes. so 768min:288 min = 8:3
Other than change completely minutes. so 768min:288 min = 8:3
(55)
BINDU said:
1 decade ago
As distance is same formula will be upstream speed X time1 =downstream speed x time 2
Time 1 =8+4/5=44/5 hrs,time2=4 hrs
(U-V)*44/5=(U+V)*4
44U-44V=20U+20V
24U-64V=0
24U=64V
U/V=64/24
=8/3.
Time 1 =8+4/5=44/5 hrs,time2=4 hrs
(U-V)*44/5=(U+V)*4
44U-44V=20U+20V
24U-64V=0
24U=64V
U/V=64/24
=8/3.
Bhomi said:
1 decade ago
Let x be the speed of boat in still water and why be the speed of stream.
Since distance covered is same in both the direction.
(x-y)*8.8 = (x+y)8.
By solving x/y = (4/1.5) i.e x:y = 8:3.
Since distance covered is same in both the direction.
(x-y)*8.8 = (x+y)8.
By solving x/y = (4/1.5) i.e x:y = 8:3.
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)
Prasanth said:
1 decade ago
@Binza
your explantation is not correct. This is not train problem to take like that. Speed of boat supported by extra speed of water current when down stream and reduced in up stream.
your explantation is not correct. This is not train problem to take like that. Speed of boat supported by extra speed of water current when down stream and reduced in up stream.
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