Aptitude - Boats and Streams - Discussion

Discussion Forum : Boats and Streams - General Questions (Q.No. 2)
2.
A man's speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The man's speed against the current is:
8.5 km/hr
9 km/hr
10 km/hr
12.5 km/hr
Answer: Option
Explanation:

Man's rate in still water = (15 - 2.5) km/hr = 12.5 km/hr.

Man's rate against the current = (12.5 - 2.5) km/hr = 10 km/hr.

Discussion:
74 comments Page 2 of 8.

Anonymous said:   4 years ago
@All.

Suppose you are riding a boat which is arriving to the beach. Naturally, the waves are in the same direction of your boat. Dont you feel easy to drive it then. Hence, the speed of waves/current supplement your boat speed. Then, it is called going downstream or going with the waves/current. Hence, By thinking vice-versa we know that we'd have to subtract the speed of the stream
(2)

Meenakshi said:   5 years ago
What is still water and current speed?
(2)

Punni said:   6 years ago
Thank you so much @Balaji.
(1)

Vaishnavi said:   6 years ago
Thanks @Sapna.
(1)

Aanchal said:   6 years ago
Su = ?
Sd = 15km/hr,
Sd = x+ y.
x+ y = 15km/hr,
x + 2.5 = 15km/hr,
x = 12.5.

x = speed of man in still water.
Sd = x -y.
15- 2.5 = 10km/hr.
(1)

Himanth said:   5 years ago
Here time has given 8hr 48min upstream, 4 hours downstream.

T=8 4/5 (While changing min to hours 48/60=4/5)

Upstream speed = Distance/time.
x-y = D/8.4/5.
D = 44/5(x-y)-------> (1)

Now downstream speed=Distance/time.
X+y=D/4,
D=4(X+y) -----------> (2)

Equate eq 1 and 2.
44/5(x-y) = 4(X+y).
24x = 64y.
X/y = 64/24,
X/y = 8:3.
(1)

Ankita Chandra said:   7 years ago
Man's speed + speed of current = 15,
Man's speed + 2.5 = 15,
Man's speed = 15 - 2.5 = 12.5,
Man's rate against the current i.e. difference between their speed ( u-v).
Man's speed - speed of current.
= 12.5 - 2.5,
= 10.
(1)

Paddu said:   8 years ago
Thank you @Mani.

HARI said:   8 years ago
Speed in current =15,
Current speed =2.5,
Upstream =15-2.5=12.5,
Downstream =15+2.5=17.5.

SHRIPAD said:   8 years ago
Thanks @Atuljain.


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