Question

Amith can row a boat d km upstream and the same distance downstream in 5 hours 15 minutes. Also, he can row the boat 2d km upstream in 7 hours. How long will it take to row the same distance 2d km downstream for Amith ?
A) 4 hrs 10 min
B) 3 hrs 15 min
C) 3 hrs 30 min
D) 4 hrs 1 min

Answer 1

Solution(By Examveda Team)

Let the speeds of boat and stream was S and V km/hr respectively.
Then, Actual Speed Downstream = (S + V) km/hr.
Actual Speed upstream = (S - V) km/hr.
Given, 

{d / (S+V)} + {d / (S-V )} =5 hrs 15 minutes = 21/4 hours. -------------- (1)
and 2d / (S+V) = 7 -------------- (2)
Now,

d / (S+V)=7/4 
Or, 2d / (S+V)=7/2

Hence, he takes 7/2hours to row 2d km distance downstream.

Answer 2

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Amith can row a boat d km upstream and the same distance downstream in 5 hours 15 minutes. Also, he can row the boat 2d km upstream in 7 hours. How long will it take to row the same distance 2d km downstream for Amith ?
A) 4 hrs 10 min
B) 3 hrs 15 min
C) 3 hrs 30 min
D) 4 hrs 1 min
$\huge\underline{\green {\textbf{D) 4 hrs 1 min}}}$

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