Latest Infosys Aptitude Question SOLUTION: Two men start from opposite banks of a river . They meet 340 meters away from one of the banks on forward journey. After that they meet at 170 meters from the other bank of the riv

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Two men start from opposite banks of a river . They meet 340 meters away from one of the banks on forward journey. After that they meet at 170 meters from the other bank of the river on their backward journey. What will be the width of the river (in meters)?

Asked In Infosys nandhakumar arumugam (9 years ago)

Unsolved Read Solution (3)

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yamuna  (9 years ago)

let p,q are two persons then their speeds be a,b->m/hr
x----340----------------------|---(d-340)---------y
in forward journey
time taken by p=340/a;
time taken by q=d-340/b;
in forward journey, time taken by p=time taken by q
so 340/a=d-340/b
a/b=340/d-340------------(1)
after that they continue their journeyand reach other banks
now in backward journey,
x---------------(d-170)--------------------------|-----170------y
distance travelled by p from meet 1 to meet 2 = (d-340)+170
distance travelled by p from meet 1 to meet 2 =340+(d-170)
now time taken by p= time taken by q
(d-340)+170/a=340+(d-170)/b
(d-340)+170/340+(d-170)=a/b---------(2)
from 1&2
340/(d-340)=(d-340)+170/340+(d-170)
340/(d-340)=d-170/d+170
340d+57800=d^2-340d-170d+57800
340d=d^2-510d
d^2-850d=0
d(d-850)=0
d=0 ord=850
so width of the river is 850

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akarsh  (9 years ago)

Let the two opposite ends of the river be X and Y and the distance between them be D meters.(i.e., width = D meters)
Let P and Q be the two men starting from the opposite banks(i.e., from X and Y respectively).
Let the speed of P and Q be A and B m/hr .

I meet :
During I meet, P travels 340m from X while Q travels (D - 340)m from Y.
Therefore, Time taken for P to travel 340m = Time taken for Q to travel (D - 340)
Or 340 / A = (D - 340) / B
Or 340 / (D - 340) = A / B ...(1)

II meet :
After crossing spot I, both of them proceed in their respective directions, reach banks and return back to cross each other at Spot II which is 170m from Y.
From Spot I to Spot II, P would had travelled a distance of (D - 340) + 170 m
From Spot I to Spot II, Q would had travelled a distance of 340 + (D - 170) m
Time taken by P to travel from Spot I to Spot II will be the same as that of Q from Spot I to Spot II

Therefore, A / (D - 340) + 170 = B / 340 + (D - 170)
Or (D - 340) + 170 / 340 + (D - 170) = A / B ...(2)
From equations I and II, we get,
340 / (D - 340) = (D - 340) + 170 / 340 + (D - 170)
340 / (D - 340) = D - 170 / D + 170
By Cross- Multiplying,
340 (D + 170) = (D - 170) (D - 340)
340D + 57800 = D2 - 170D - 340D + 57800
D2 - 850D = 0
By Factorizing,
D(D - 850) = 0
D = 850
Hence the width of the river = 850 m

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Vivek Vimal  (3 years ago)

Initial Case: D = S*T
Second Case: D = (S-200)*(T+1/2)
Solve both equation u will get t= +-1 so answer is +1

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