Question

The speed of a boat in upstream is 18km/h and upstream speed is 500% more than current speed then find the distance covered by boat in downstream in 3 hours

Answer 1

Let speed of boat in ground frame is "v"

Given that upstream speed is 500% more than the speed of current

So the speed of current will be "x"

then upstream speed will be "6x"

given that upstream speed is 18 km/h

so we can say

$6x = 18$

$x = 3 km/s$

so the current speed is 3 km/h

now we can say

upstream speed = boat speed - current speed

$18 km/h = v_b - 3 km/h$

$v_b = 21 km/h$

now during downstream net speed is given by

$v_{down} = v_b + v_{current}$

$v_{down} = 21 + 3 = 24 km/h$

now the distance covered in 3 hour is given by

$d = v_{down} * time$

$d = 24* 3 = 72 km$

so the distance covered by the boat in downstream will be 72 km