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:
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 4 of 8.
Abc said:
8 years ago
Not getting. Please, someone, help me to get it.
Peauts said:
8 years ago
You are right @Deepika
a=u+v(speed of downstream/speed of man with the stream(i.e)he is going along with the stream)
u=a-v (speed of the man alone)=12.5
b=u-v
if b is given:
put b=u-v
So, u=b+v.
a=u+v(speed of downstream/speed of man with the stream(i.e)he is going along with the stream)
u=a-v (speed of the man alone)=12.5
b=u-v
if b is given:
put b=u-v
So, u=b+v.
Akash r said:
8 years ago
Thank you @Balaji.
Deepika said:
8 years ago
Sir, I have one doubt.
Given downstream speed (i.e speed of boat with stream)is 15 km/hr .asked ..upstream speed is( boat speed(u)- stream speed(v)).
Here to find the boat speed we use boat speed= downstream speed - stream speed.what should we do if upstream speed( speed of boat against stream) is given in the question.
Should we do like this, boat speed=upstream speed+ stream speed.
Given downstream speed (i.e speed of boat with stream)is 15 km/hr .asked ..upstream speed is( boat speed(u)- stream speed(v)).
Here to find the boat speed we use boat speed= downstream speed - stream speed.what should we do if upstream speed( speed of boat against stream) is given in the question.
Should we do like this, boat speed=upstream speed+ stream speed.
Mahima said:
8 years ago
Thank you @Balaji. You explained it very clearly.
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?
If both are same I am getting 12.5 as an answer for this question, can anyone clarify it?
Shyam said:
9 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.
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.
Swathi said:
9 years ago
Why can't we use the formula 1/2 (a-b) to get the upstream value directly?
That time the answer would be 20 km/hr. Please tell me.
That time the answer would be 20 km/hr. Please tell me.
Arun said:
9 years ago
Stream direction is same while man's direction is opposite in the case of upstream.
Then why we subtract stream instead of the man's speed?
Then why we subtract stream instead of the man's speed?
Shahid said:
9 years ago
Very good explanation, thank you all.
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