Question

A man takes 16/9 times as long to row a distance upstream as to row the same distance downstream. What is the speed of the boat in still water if it takes 3 hours to travel 38.4 km downstream ? (

Answer 1

Answer: 10

Step-by-step explanation:  

Let the speed of the boat in still water = x kmph

Speed of current = y kmph

Speed upstream is (b – r), and the speed downstream is (b + r).

speed = distance/time

For downstream;

38.4/(x+y) = 3

(x+y) = 38.4/3 = 12.8kmph  

For upstream;  

38.4/(x-y) = (16/9) *3 = 38.4/(x-y) = 16/3

=> x – y =  (38.4*3)/(16) = 7.2 kmph

Therefore

speed of boat in still water = (12.8+7.2)/2 = 10 kmph