Question

A boat goes up a river 20 km and down the river 24 km in 8 hours. It also goes up the river 30 km and down the river 28 km in 11 hours. Find the speed of the boat and the river?

Answer 1

Answer:

Step-by-step explanation:

let speed in still water= x

let speed of current = y

speed upstream = x-y

speed downstream = x+y

now,  case 1,

                     upstream= 20 km ;  downstream = 24 km

when upstream,

time = distance/ speed

time 1 = 20/x-y

time 2 = 24/x+y

now , t1+ t2 = total time taken

20/x-y  + 24/ x+y = 8

solve by reduction method to get an equation of two variables.

same in case 2,

time 1 = 30/x-y

time 2 = 28/x+y

total time = 30/x-y + 28/x+y= 11

solve to get another equation.

solve both equations, and get the value of x and y