A boat can cover 25 km upstream and 42 km downstream together in 7 hours Also it can cover 30 km ups...........

Quantitative Aptitude(Banking) Boats and Streams

A boat can cover 25 km upstream and 42 km downstream together in 7 hours. Also it can cover 30 km upstream and 63 km downstream together in 9 hours. What is the speed of the boat in still water?

13 km/hr

8 km/hr

7 km/hr

11 km/hr

छोटे Courses बड़े Results

Master Boats and Streams

Prepare through Micro-courses

Try Now

Explanation:

Solution:
Upstream speed in both cases is 25 and 30 resp. Ratio is 25 : 30 = 5 : 6. So let times in both cases be 5x and 6x
Downstream speed in both cases is 42 and 63 resp. Ratio is 42 : 63 = 2 : 3. So let times in both cases be 2y and 3y
So 5x + 2y = 7
and 6x + 3y = 9
Solve both, x = 1, y = 1
So upstream speed is = 25/5x = 5 km/hr
And downstream = 42/2y = 21 km/hr
So speed of boat is 1/2 * (5+21) = 13