Question

A motor boat covers a certain distance downstream in a river in 3 hours. it covers the same distance upstream in 3 hours and a half.if the speed of water is 1.5 km/h. then the speed of the boat in still water is

Answer 1

Let distance coverage be xkm
In upstream (x/3. 5)kmph is speedU
In downstream Speed=(x/3)kmph
Speed of boat in still water be v
Then v+1.5=x/3...(1)
& v-1.5=x/3.5...(2)
(1)-(2)=>3=x{(1/3)-(1/3.5)}
=>x=63
So from(1)=>v=(63/3)-1.5=21-1.5=19.5km/h

Answer 2

Answer:

19.5 km/hr

Step-by-step explanation:

Let the speed of boat in still water be x

Upstream speed = x-1.5

Time for upstream= 3.5 hours

Distance = Speed * Time

Distance =3.5(x-1.5)

Downstream speed = x+1.5

Time for downstream = 3 hours

Distance = Speed * Time

Distance =3(x+1.5)

Distance must be same

So, 3.5(x-1.5)=3(x+1.5)

x=19.5

Hence the speed of the boat in still water is 19.5 km/hr