A man can row three-quarters of a kilometre against the stream in 11 1/4 minutes and down the stream in 7 1/2 minutes. The speed (in km/hr) of the man in still water is:

A man can row three-quarters of a kilometre against the stream in 11 1-div-1by4 minutes and down the stream in 7 1-div-1by2 minutes. The speed (in km/hr) of the man in still water is:

[A].	2
[B].	3
[C].	4
[D].	5

Answer: Option D

Explanation:

We can write three-quarters of a kilometre as 750 metres,

and 11 1-div-1by4 minutes as 675 seconds.

Rate upstream =		750	m/sec	=	10	m/sec.
		675			9

Rate downstream =		750	m/sec	=	5	m/sec.
		450			3

Rate in still water =	1		10	+	5	m/sec
	2		9		3

=	25	m/sec
	18

=		25	x	18	km/hr
		18		5

= 5 km/hr.

Aptitude :: Boats and Streams : More Exercises

Boats and Streams - General Questions

A man can row three-quarters of a kilometre against the stream in 11 1/4 minutes and down the stream in 7 1/2 minutes. The speed (in km/hr) of the man in still water is:

Aptitude :: Boats and Streams : More Exercises

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