Question

a boat covers distance between two points down stream in 12hours and same distance down stream withits engine cuttoff in 36 hrs then it covres same distance up stream is

Answer 1

Answer:

36 h

Step-by-step explanation:

It takes 12h to reach  the distant with the velocity of the boat and the velocity of the stream. When the engines are off, its only the velocity of the stream takes the boat to the distant in 36h.

distant (d)  

V=D/T

velocity of the stream (Vs)

velocity of the boat (Vb)

The boat travels a distance (d) downstream in 12h

Vs + Vb =d/12 ---------(i)

(both velocities are in the same direction)

When the engines are off there is only the velocity of the stream.

Vs = d/36

substitute in (i)

d/36  +  Vb = d/12  => Vb = d/18

If the boat travel a same distance upstream

Vb - Vs  (because the velocities are in different directions)

i.e  d/18 - d/36 = d/36

so that it will take 36h to travel the same distant upstream with the engines on.