BOATS & STREAMS - Aptitude Interview Questions with Answers

BOATS & STREAMS – Aptitude Interview Questions with Answers

This blog explains about BOATS & STREAMS – Aptitude Interview Questions with Answers and is given below :

1. A man can row at 5 kmph in still water. If the velocity of current is 1 kmph and it takes him 1 hour to row to a place and come back, how far is the place?

A	2.4 km
B	2.5 km
C	3 km
D	3.6 km

Answer: Option A

Explanation:

Speed downstream = (5 + 1) kmph = 6 kmph.

Speed upstream = (5 – 1) kmph = 4 kmph.

Let the required distance be x km.

Then,	x	+	x	= 1
	6		4

2x + 3x = 12

5x = 12

x = 2.4 km.

2 . 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 hr 15 min
D	1 hr 30 min

Answer: Option C

Explanation:

Rate downstream =		1	x 60	km/hr = 6 km/hr.
		10

Rate upstream = 2 km/hr.

Speed in still water =	1	(6 + 2) km/hr = 4 km/hr.
	2

Required time =		5	hrs = 1	1	hrs = 1 hr 15 min.
		4		4

3 . A man rows to a place 48 km distant and come back in 14 hours. He finds that he can row 4 km with the stream in the same time as 3 km against the stream. The rate of the stream is:

A	1 km/hr
B	1.5 km/hr
C	2 km/hr
D	2.5 km/hr

Answer: Option A

Explanation:

Suppose he move 4 km downstream in x hours. Then,

Speed downstream =		4		km/hr.
		x

Speed upstream =		3		km/hr.
		x

	48	+	48	= 14 or x =	1	.
	(4/x)		(3/x)		2

So, Speed downstream = 8 km/hr, Speed upstream = 6 km/hr.

Rate of the stream =	1	(8 – 6) km/hr = 1 km/hr.
	2

4 . 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

Answer: Option C

Explanation:

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.

5 . A motorboat, whose speed in 15 km/hr in still water goes 30 km downstream and comes back in a total of 4 hours 30 minutes. The speed of the stream (in km/hr) is:

A	4
B	5
C	6
D	10

Answer: Option B

Explanation:

Let the speed of the stream be x km/hr. Then,

Speed downstream = (15 + x) km/hr,

Speed upstream = (15 – x) km/hr.

	30	+	30	= 4	1
	(15 + x)		(15 – x)		2

	900	=	9
	225 – x²		2

9x² = 225

x² = 25

x = 5 km/hr.

6 . A boat running upstream takes 8 hours 48 minutes to cover a certain distance, while it takes 4 hours to cover the same distance running downstream. What is the ratio between the speed of the boat and speed of the water current respectively?

A	2 : 1
B	3 : 2
C	8 : 3
D	Cannot be determined
E	None of these

Answer: Option C

Explanation:

Let the man’s rate upstream be x kmph and that downstream be y kmph.

Then, distance covered upstream in 8 hrs 48 min = Distance covered downstream in 4 hrs.

		x x 8	4		= (y x 4)
			5

	44	x =4y
	5

y =	11	x.
	5

Required ratio =		y + x		:		y – x
		2				2

=		16x	x	1		:		6x	x	1
		5		2				5		2

=	8	:	3
	5		5

= 8 : 3.

7 .In one hour, a boat goes 11 km/hr along the stream and 5 km/hr against the stream. The speed of the boat in still water (in km/hr) is:

A	3 km/hr
B	5 km/hr
C	8 km/hr
D	9 km/hr

Answer: Option C

Explanation:

Speed in still water =	1	(11 + 5) kmph = 8 kmph.

8 . A boat running downstream covers a distance of 16 km in 2 hours while for covering the same distance upstream, it takes 4 hours. What is the speed of the boat in still water?

A	4 km/hr
B	6 km/hr
C	8 km/hr
D	Data inadequate

Answer: Option B

Explanation:

Rate downstream =		16	kmph = 8 kmph.
		2

Rate upstream =		16	kmph = 4 kmph.
		4

Speed in still water =	1	(8 + 4) kmph = 6 kmph.
	2

9 .The speed of a boat in still water in 15 km/hr and the rate of current is 3 km/hr. The distance travelled downstream in 12 minutes is:

A	1.2 km
B	1.8 km
C	2.4 km
D	3.6 km

Answer: Option D

Explanation:

Speed downstream = (15 + 3) kmph = 18 kmph.

Distance travelled =		18 x	12	km = 3.6 km.
			60

10 . A boat covers a certain distance downstream in 1 hour, while it comes back in 1 hours. If the speed of the stream be 3 kmph, what is the speed of the boat in still water?