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Numerical Ability
Boats and Streams
A boat travels 300m upstream in 15 mins. its speed downstream is 8/5 time its upstream . which of the following option is correct?
a.speed of current=12/10 of speed of boat
b.speed of current=3/13 of speed of boat
c.speed of current=9/13 of speed of boat
Read Solution (Total 9)
-
- b. Speed of current=3/13 of speed of boat
Let the speed of the boat=x and current=y m/min, then
Time taken in upstream = 300/(x-y) = 15 => x - y = 20 ---(i) and
Downstream speed = (8/5)*Upstream speed
=> x+y = (8/5)*(x-y) => 3x - 13y = 0 ---(ii)
Solving (i) & (ii), x=26, y=6
Hence, speed of current/speed of the boat = 6/26 = 3/13 - 6 years agoHelpfull: Yes(6) No(0)
- This question won't even need the distance and time.
If speed of boat =x and speed of current=y then
(x+y)=8/5(x-y)
=>y+8y/5=8x/5-x
=>13y/5=3x/5
=>y=13x/3
So b is the correct ans - 6 years agoHelpfull: Yes(6) No(0)
- Upstream speed = 300/15 = 20m/min
Downstream speed = 8/ 5 ×20 = 32m/min
Boat speed= (32+20)/2=26
Stream speed = (32-20)/2=6 - 6 years agoHelpfull: Yes(3) No(0)
- In 15 mins boat travels 300 mtr
So, in 60 mins=(300*4)=1200mtr
So, (u-v)=1200
Thus we get (u+v)=1920
Sloving this two equation we get u=1560 and v=360
Now (v:u)=360:1560=3:13 - 6 years agoHelpfull: Yes(1) No(0)
- time taken for going upstream= (distance travelled/ Speed of boat(B)-Speed of Stream(S))
300/(B-S)=15
B-S= 300/15= 20------------(1)
According to the condition:
B+S=8/5(B-S)
B+S=32---------------------------(2)
taking the two equation we get:
B=26 and S=6
S/B=6/26=3/13
S=3/13(B) - 6 years agoHelpfull: Yes(1) No(2)
- B is the rht answer
- 6 years agoHelpfull: Yes(0) No(2)
- let us assume upstream=x-y
downstream=x+y
300/(x-y)=15
x-y=20
x+y=(8/5)(x-y)
3x-13y=0--->3x=13y--->y/x=3/13
speed of the current=y/x=3/13 - 6 years agoHelpfull: Yes(0) No(0)
- Answer is b
- 6 years agoHelpfull: Yes(0) No(0)
- b. speed of current=3/13 of speed of boat
s+v/s-v = 8/5
s-v = 300/15 = 20 m/min
so, s+v=32 m/min
s=6/26=3/13 v - 4 years agoHelpfull: Yes(0) No(0)
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