Question

A boat covers 32km upstream and 36km downstream in 7 hours. Also it covers 40km upstream and 48km
Find downstream in 9 hours. the speed of boat in still water and that of the stream.

Answer 1

Answer:

the speed of boat in still water m=10km/hr

the speed of boat in stream s=2km/hr

Step-by-step explanation:

we know,

upstream=(m-s)km /hr

downstream=(m+s) km/hr

m is the speed of boat in still water

s is the speed of boat in stream

Speed=Distance/Time

Time=Distance/Speed

Given,

A boat covers 32km upstream and 36km downstream in 7 hours.

7 =32/(m-s)+36/(m+s)   --------(1)

Also it covers 40km upstream and 48km   downstream in 9 hours.

9=40/(m-s)+48/(m+s)  -----------(2)

by dividing Eq(1) by (2)

7/9=32(m+s)+36(m-s)/40(m+s)+48(m-s)

7(40m+40s+48m-48s)=9(32m+32s+36m-36s)

7(88m-8s)=9(68m-4s)

616m-56s=612-36s

4m=20s

m/s=20/4

let m/s=5x/1x

substitute m and s in Eq(1)

7=32/(5x-1x)+36/(5x+1x)

7=32/4x+36/6x

7=8/x+6/x

7x=14

x=2

m is 5x

5*2=10 km/hr

S is 1 x=2km/hr