Question

When speed of boat in still water is
increased by 10%,
then it covers 12 km more
downstream distance than
actual downstream distance covered
and when its speed
in still water is decreased by 20%,
then it covers 24 km
less downstream distance than
actual downstream
distance covered. What is the actual
speed of boat in still water​

Answer 1

Answer:

time taken to travel upstream : time taken to travel downstream = 2 : 1

speed upstream : speed downstream = 1 : 2 (as speed is inversely proportional to time when distance is constant)

Let speed upstream= x and speed downstream = 2x

Rate of the stream = (2x-x)/2 =x/2

x/2 is given as 1 km/hr

=> x = 2km/hr

speed of the board in still water = 1/2 (2x+x) = 3x/2 = 6/2 = 3 km/hr