# Tips and Tricks on Boats and Streams related Aptitude Problems

1. Downstream/Upstream:In water, the direction along the stream is called downstream. And, the direction against the stream is called upstream.
2. If the speed of a boat in still water is u km/hr and the speed of the stream is v km/hr, then:

Speed downstream = (u + v) km/hr.

Speed upstream = (u – v) km/hr.

3. If the speed downstream is a km/hr and the speed upstream is b km/hr, then:
 Speed in still water = 1 (a + b) km/hr. 2
 Rate of stream = 1 (a – b) km/hr. 2
1.A boat can travel with a speed of 13 km/hr in still water. If the speed of the stream is 4 km/hr, find the time taken by the boat to go 68 km downstream.
 A. 2 hours B. 3 hours C. 4 hours D. 5 hours

Explanation:

Speed downstream = (13 + 4) km/hr = 17 km/hr.

 Time taken to travel 68 km downstream = 68 hrs = 4 hrs. 17

2.A man’s speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The man’s speed against the current is:
 A. 8.5 km/hr B. 9 km/hr C. 10 km/hr D. 12.5 km/hr

Explanation:

Man’s rate in still water = (15 – 2.5) km/hr = 12.5 km/hr.

Man’s rate against the current = (12.5 – 2.5) km/hr = 10 km/hr.