?
The speed of a boat in still water is 10 km/hr. If it can travel 26 km downstream and 14 km upstream at the same time, the speed of the stream is-
Answer & Solution
Correct Answer:
Option
C
Let the speed of the stream be x km/hr
Then speed downstream = (10 + x) km/hr
Speed upstream
$$\eqalign{ & {\text{ = }}\left( {10 - x} \right)km/hr \cr & \therefore \frac{{26}}{{\left( {10 + x} \right)}} = \frac{{14}}{{\left( {10 - x} \right)}} \cr & \Rightarrow 260 - 26x = 140 + 14x \cr & \Rightarrow 40x = 120 \cr & \Rightarrow x = 3\,km/hr \cr} $$
Then speed downstream = (10 + x) km/hr
Speed upstream
$$\eqalign{ & {\text{ = }}\left( {10 - x} \right)km/hr \cr & \therefore \frac{{26}}{{\left( {10 + x} \right)}} = \frac{{14}}{{\left( {10 - x} \right)}} \cr & \Rightarrow 260 - 26x = 140 + 14x \cr & \Rightarrow 40x = 120 \cr & \Rightarrow x = 3\,km/hr \cr} $$
Join the Discussion
Login to post a comment or share your explanation.
Login