Question

Pratap Puri rowed 14 miles down a river in 2 ​hours, but the return trip took him 3 and one half hours. Find the rate Pratap can row in still water and find the rate of the current. Let x equals rate Pratap can row in still water and y equals rate of the current. What is the rate that Pratap rows in still​ water?

Answer 1

let the rate in still water be x and rate of the current be y.
speed down the river is:
speed=distance/time
speed=14/2=7 mi/h

speed up the river is:
speed=(14)/(3.5)=4 mi/hr
thus total speed downstream and upstream will be:
x+y=7...i
x-y=4.......ii
adding the above equations i and ii we get:
2x=11
x=5.5 mi/hr
thus
y=5-5.5=1.5 mi/r
thus the speed in still waters is 5.5 mi/hr
speed of current is 1.5 mi/hr