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:
72 comments Page 2 of 8.

Meenakshi said:   4 years ago
What is still water and current speed?
(2)

Aanchal said:   5 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)

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)

Vaishnavi said:   5 years ago
Thanks @Sapna.
(1)

Punni said:   5 years ago
Thank you so much @Balaji.
(1)

Himanth said:   4 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)

Ayaan mansoori said:   3 years ago
Yes, you are right. Thanks @Balaji.
(1)

Paddu said:   7 years ago
Thank you @Mani.

Shyam said:   8 years ago
@Vishal.

15 is the speed of the man "with" speed of current i.e., 15 is the speed of man in downstream.
That means M + S = 15; S = 2.5.
Finally, man's speed =15-2.5 = 12.5.

Sibani said:   8 years ago
Is both the terms rate of stream and speed of the current are same.
If both are same I am getting 12.5 as an answer for this question, can anyone clarify it?


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