A man rows down a river 18 km in 4 hours with the stream and returns in 10 hours Consider the follow...........

Quantitative Aptitude (CDS) Boats and Streams

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A man rows down a river 18 km in 4 hours with the stream and returns in 10 hours. Consider the following statements:

1. The speed of the man against the stream is 1.8 km/hr.

2. The speed of the man in still water is 3.15 km/hr

Which of the above statements are correct?

1 and 2 only

2 and 3 only

1 and 3 only

1, 2 and 3

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Explanation:

Let the speed of the man in still water be x km/hr and
let the speed of the stream be y km/hr
Speed of the man downstream = x + y km/hr
Speed of the man upstream = x -y km/hr
Therefore x+y=184 ….. (i)
x−y=18 / 10=1.8km/hr …….. (ii)
Solving these equations by elimination method, we get
2x=18 / 4+1.8=4.5+1.8=6.3=>x = 3.15km/hr…….(iii)
3.15−y=1.8=>y=1.35km/hr ………(iv)
Therefore, equations (ii), (iii) and (iv) implies that all the given statements are correct