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 4 of 12.
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
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
(56)
Chandu said:
2 months ago
Upstream = boat - stream.
Downstream = boat + stream.
Distance is the same in both cases.
So,D(u.s) = D(d.s).
S×t = s × t.
(Boat+stream) × 8.8h = (boat - stream) × 4h.
Which gives the ratio.
Downstream = boat + stream.
Distance is the same in both cases.
So,D(u.s) = D(d.s).
S×t = s × t.
(Boat+stream) × 8.8h = (boat - stream) × 4h.
Which gives the ratio.
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.
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