CBSE Class 8 Answered

Let the speed of the steamer in still water be x km/h and distance be d.

Therefore, speed of steamer in downstream = x + 1

Speed of steamer in upstream = x − 1

Distance covered by steamer in upstream = 10(x − 1)        ......(1)

Distance covered by steamer in downstream = 9(x + 1)     ......(2)

Since, the distance covered going downstream will be same as the distance covered going upstream.

Therefore, 10(x − 1) = 9(x + 1)

i.e. 10x – 10 = 9x + 9

i.e. 10x − 9x = 9 + 10

i.e. x = 19 km/h

Putting x in (1), we get

Distance = 10(19 − 1) = 180km

Hence, the speed of the steamer in still water is 19km/h and the distance between the ports is 180km.