Question

15. A boat goes 16km upstream and 24km downstream in 6hrs. It can go 12km up and 36km down in the same time.Find the speed of the boat in still water and the speed of the stream.

Answer 1

let  x = speed  of  boat  in still  water  and  y = speed  of  stream,  hence

speed  upstream =  x - y  and  speed  downstream =  x + y

16 / x - y  +  24 / x +y = 6  also  12 / x - y   +  36 / x + y  =  6,  hence

4 / x - y  =   12 / x + y   hence   x +y / x - y  =  3/1  

using  componendo, dividendo,  we  get  x = 2  and  y =1