a2zinterviews

10.	In one hour, a boat goes 11 km along the stream and 5 km against the stream. The speed of the boat in still water in ( km/hr) is
	A.  3
	B.  5
	C.  8
	D.  9

Solution

Speed in still water = 1/2(11+5) km/hr = 8 km/hr.

11.	A man can row three - quarters of a kilometer against the stream in 11¼minutes. The speed(in km/hr) of the man in still water is
	A.  2
	B.  3
	C.  4
	D.  5

Solution

Rate upstream = (750 / 675)m/sec = (10 / 9) m/ sec. Rate downstream = (750 / 450) =(5 / 3) m/sec Rate in still water = 1/2(10 /9 + 5/3) = (25/18x18/5)km/hr = 5 km/hr.

12.	If a man rows at the rate of 5 kmph in still water and his rate against the current is 3.5 kmph, then the man’s rate along the current is
	A.  4.25 kmnph
	B.  6 kmph
	C.  6.5 kmph
	D.  8.5 kmph

Solution

Let the rate along the current be x kmph. Then, = (1 / 2(x+3.5))= 5 x= 6.5 kmph.

13.	Speed of a boat in standing water is 9 kmph and the speed of the stream is 1. 5 kmph. A man rows to a place at a distance of 105 km and comes back to the starting point. The total time taken by him is
	A.  16 hours
	B.  18 hours
	C.  20 hours
	D.  24 hours

Solution

Speed upsteram = 7.5 kmph. Speed downsteram = 10.5 kmph. Total time taken =[10.5/7.5 + 105/10.5]hours = 24 hours.