Aptitude - Boats and Streams - Discussion
Discussion Forum : Boats and Streams - General Questions (Q.No. 14)
14.
A man takes twice as long to row a distance against the stream as to row the same distance in favour of the stream. The ratio of the speed of the boat (in still water) and the stream is:
Answer: Option
Explanation:
Let man's rate upstream be x kmph.
Then, his rate downstream = 2x kmph.
 (Speed in still water) : (Speed of stream) = |
 |
2x + x |  |
: | |
2x - x | |
| 2 | 2 |
| = | 3x | : | x |
| 2 | 2 |
= 3 : 1.
Discussion:
30 comments Page 2 of 3.
Pranay pal said:
9 years ago
Let,
Boat speed=b
Speed of water= w
Upstream speed =b"w= x kmph---> eqn a.
Downstream speed= b+w= 2x kmph
b+w= 2x kmph
b+w= 2(b"w) kmph
3w= b kmph
Putting value of w in equation a.
M/x = 3/2
Answer would be 3:2.
Boat speed=b
Speed of water= w
Upstream speed =b"w= x kmph---> eqn a.
Downstream speed= b+w= 2x kmph
b+w= 2x kmph
b+w= 2(b"w) kmph
3w= b kmph
Putting value of w in equation a.
M/x = 3/2
Answer would be 3:2.
Omkar said:
1 decade ago
Let t1 = 2t2.
T1/T2 = 2/1.
But time is inversely proportional to speed. Speed = Distance/Time.
So s1/s2 = 1/2.
Speed of boat in still water = 1/2(2+1) = 3/2.
Speed of stream = 1/2(2-1) = 1/2.
3/2/1/2 = 3:1.
T1/T2 = 2/1.
But time is inversely proportional to speed. Speed = Distance/Time.
So s1/s2 = 1/2.
Speed of boat in still water = 1/2(2+1) = 3/2.
Speed of stream = 1/2(2-1) = 1/2.
3/2/1/2 = 3:1.
Fathima Sulfikkar said:
5 years ago
Distance is same.
D (up)=D (down); also t (u)= 2t (d)
Speed of boat=b: speed of current = s.
D (u) = D (d).
t (u)(b-s) = t (v)(b+s).
2t (v)(b-s) = t (v)(b+s).
2b-2s = b+s.
2b-b = s+2s.
b = 3s.
b/s = 3/1.
D (up)=D (down); also t (u)= 2t (d)
Speed of boat=b: speed of current = s.
D (u) = D (d).
t (u)(b-s) = t (v)(b+s).
2t (v)(b-s) = t (v)(b+s).
2b-2s = b+s.
2b-b = s+2s.
b = 3s.
b/s = 3/1.
(3)
Vishi said:
8 years ago
Boat speed(B) +stream speed (S).
B+S = x
B-S = 2x
BY adding
2B = 3x
B= 1.5 x
By substracting
2S = -x
S= -.5 on neglecting - sign .5x
Ration becomes .5 : 1.5
Which is 1:3 also
Stream speed : boat speed.
B+S = x
B-S = 2x
BY adding
2B = 3x
B= 1.5 x
By substracting
2S = -x
S= -.5 on neglecting - sign .5x
Ration becomes .5 : 1.5
Which is 1:3 also
Stream speed : boat speed.
Ragi k r said:
6 years ago
The speed of boat= B, speed of river= R.
upstream=x=B-R -----> (1)
downstream=2x=B+R -----> (2)
So, (1)+(2).
2B=3x
B=x(3/2)
B+R=2x.
=>R=2x-B =>R=2x-(3/2)x =>R=x/2.
B:R=3/2 : 1/2 = 3:1.
upstream=x=B-R -----> (1)
downstream=2x=B+R -----> (2)
So, (1)+(2).
2B=3x
B=x(3/2)
B+R=2x.
=>R=2x-B =>R=2x-(3/2)x =>R=x/2.
B:R=3/2 : 1/2 = 3:1.
Niklu Rana said:
10 years ago
Let the speed of still water = X and the speed of stream = Y;
As given here, Speed against the stream = 1/2*(Speed in favor of the stream);
Therefor 2X-2Y = X+ Y;
So that, X/Y = 3/1.
As given here, Speed against the stream = 1/2*(Speed in favor of the stream);
Therefor 2X-2Y = X+ Y;
So that, X/Y = 3/1.
Mani said:
5 years ago
Hi, but in this question upstream is same as downstream then for both it would be twice then how you could say upstream is x downstream is 2x?
(2)
Shalinee said:
7 years ago
Here we use this formula and simply find the ratio.
Sb/Ss =n+1/n-1 then,
Sb/Ss = 2+1/2-1,
Sb/Ss =3/1 so.
Then we will get,
Sb:Ss = 3:1.
Sb/Ss =n+1/n-1 then,
Sb/Ss = 2+1/2-1,
Sb/Ss =3/1 so.
Then we will get,
Sb:Ss = 3:1.
(2)
Mohit said:
8 years ago
Downstream distance(x) : upstream distance(y)= 2:1.
Boat speed(u) : stream speed(v)= x+y : x-y.
= 3 : 1 --> answer.
Boat speed(u) : stream speed(v)= x+y : x-y.
= 3 : 1 --> answer.
Ravitheja said:
1 decade ago
Speed of still water is A = X.
Speed upstream is x/2.
Speed downstream B = 2xX = 2X+X = 3X.
B/A = 3/1 = 3:1.
Speed upstream is x/2.
Speed downstream B = 2xX = 2X+X = 3X.
B/A = 3/1 = 3:1.
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