## 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

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

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

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

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

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

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

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

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

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?
 A 12 kmph B 13 kmph C 14 kmph D 15 kmph E None of these

Explanation:

Let the speed of the boat in still water be x kmph. Then,

Speed downstream = (x + 3) kmph,

Speed upstream = (x – 3) kmph.

 (x + 3) x 1 = (x – 3) x 3 2

2x + 6 = 3x – 9