Tips And Tricks And Shortcuts On Boats And Streams
Tips, Tricks And Shortcuts for Boats & Streams Question
Here, are quick and easy tips and tricks for you to solve Boats and Streams questions quickly, easily, and efficiently in competitive exams. The boats and streams problems are based on the concepts of time, speed, and distance. However, a few adjustments need to be made in case of such problems.
Type 1: Tips and Tricks for Finding Speed of Boat
- Boats and Streams Tips and Trick and Shortcuts
Speed of the boat in still water = 1/2 (Downstream speed + Upstream speed)
Downstream speed = Speed of boat in still water + Speed of stream
Upstream speed = Speed of boat in still water – Speed of stream
Question 1:A man rows a boat at 12 km/h along the stream and 8 km/h against the stream. Find the speed of the boat in still water.
Solution: Downstream speed of the boat = 12 km/h
Upstream speed of the boat = 8 km/h
Speed of the boat in still water = 1/2*(Downstream speed + Upstream speed)
= 1/2 (12 + 8)
= 10 km/h
Correct option: B
Type 2: Tips and Tricks to Find the Speed of Stream
- Tips and Trick and Shortcuts for Boats and Streams
Speed of stream = 1/2 *(Downstream speed – upstream speed)
Speed downstream = (u + v ) km/hr.
Speed upstream = (u – v ) km/hr.
Question 1:A boat whose speed in 15 km/hr in still water goes 30 km downstream and it takes 4 hours 30 minutes to come back. Find the speed of the stream?
A . 25km/hr
Solution: Let the speed of the stream = x
Therefore, speed downstream = 15 + x
Speed upstream = 15 – x
30/(15+x) + 30/(15-x) = 4hr 30 min
30/(15+x)+ 30/(15-x) = 9/2
On solving we get
x = 5km/hr
Correct option: D
Type 3: Using Man’s Still Water Speed Calculate Stream’s Speed
Question 1:A sailor can row 6 km/h in still water. It takes him twice as long to row up as to row down the river. Find the speed of the stream.
A. 6 km/ hr
B. 5 km/ hr
C. 3 km/ hr
D. 2 km/ hr
Solution: Let sailor’s speed in upstream = x
Downstream speed = 2x (As given in the question, his downstream speed is twice of upstream speed)
Man’s speed in still water = 1/2 (Upstream speed + Downstream speed)
= 1/2 (x + 2x) = 3x/2
3x/2 = 6 (sailor can row 6 km/h in still water)
x = 4 km/hr
Therefore, upstream speed = x = 4 km/hr
Downstream speed = 2x = 2 * 4 = 8 km/hr
Speed of stream = 1/2* (Downstream speed – Upstream speed)
= 1/2 (8 – 4)
= 2 km/ hr
Correct option: D