Question

40. A motor boat covers the distance between the two
localities on a river in 6 hours downstream and in 8
hours upstream. The speed of the boat is how many
times that of the river?​

Answer 1

Answer:

speed of boat is 7 times the speed of river

let speed of boat be v km/h (in still water) and speedof river be y km/h and distance be x km

NOW ,

speed of boat downstream=v+y and also

v+y=x/time taken to cover x km downstream

v+y=x/6 now, x=(v+y)*6----------<1>eqn.

speed of boat upstream= v-y and also,

v-y=x/time taken to cover x km upstream

v-y=x/8 also x=(v-y)*8----------<2> eqn.

since eqn. 1 and 2 hbe equal results hence eqn 1=2 so,

6(v+y)=8(v-y)

3v+3y=4v-4y

3y+4y=4v-3v

7y=v

hence speed of boat is seven times the speed of river. hope it helps