a2zinterviews

6.	A boat covers a certain distance downstream in I hour, while it comes back in 1½ hours. If the speed of the stream be 3 kmph. what is the speed of the boat in still Water?
	A.  12kmph
	B.  13kmph
	C.  15kmph
	D.  16kmph

Solution

Let the speed of the boat in still water be x kmph. Then, Speed downsteram = (x + 3) kmph. Speed upsteram = (x - 3) kmph. = (x+3)x1 = (x - 3)x3/2 kmph. = 2x+6 = 3x-9 x= 15 kmph.

7.	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

Solution

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.

8.	A man can row upstream at 7 kmph and downstream at 10 kmph.Find man's rate in still water and the rate of current?
	A.  1.2 km/hr
	B.  1.5 km/hr
	C.  1.6 km/hr
	D.  1.8 km/hr

Solution

Rate in still water = 1 / 2 (10 + 7) km/hr = 8.5 km/hr. Rate of current = 1 / 2(10 - 7) km/hr = 1.5 km/hr.

9.	A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take to go 5 km in stationary water?
	A.  40 minutes
	B.  1 hour
	C.  1 hour 15 min
	D.  1 hour 30 min

Solution

Rate downstream = (1 / 10 x 60)km/hr = 6 km / hr. Rate upstream = 2 km/hr. Speed in still water = 1 / 2(6 + 2)km/hr = 4 km. Required time = (5 / 4) km/hr = 1x 1/4 km/hr = 1 hr 15 min.