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Boats and Streams ( 11 to 15 ):

# APTITUDE QUESTIONS (BOATS AND STREAMS):

11. A boat can travel with a speed of 11 km/hr in still water. If the speed of the stream is 3 km/hr, find the time taken by the boat to go 70 km downstream.

A) 2 hours

B) 3 hours

C) 4 hours

D) 5 hours

E) None of these

View Answer

Answer: option (D)

Explanation:

Speed downstream = (11 + 3) km/hr = 14 km/hr

Time taken to travel 68 km downstream = (70/14) hrs = 5 hrs.

12. Speed of a boat in standing water is 9 km/hr and the speed of the stream is 1.5 km/hr. A woman rows to a place at a distance of 105 km and comes back to the starting point. The total time taken by her is:

A) 16 hours

B) 18 hours

C) 20 hours

D) 24 hours

E) None of these

View Answer

Answer: option (D)

Explanation:

Speed upstream = 7.5 km/hr; Speed downstream = 10.5 km/hr

∴ Total time taken = (10.5/7.5+10.5/10.5) hours = 24 hours

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

A) 1.2 km

B) 3 km

C) 2.4 km

D) 3.6 km

E) None of these

View Answer

Answer: option (B)

Explanation:

Speed downstream = (12 + 3) = 15 km/hr

Distance travelled = (15*12/60) km = 3 km

14. A man can row at 6 km/hr in still water. If the velocity of current is 1 km/hr and it takes him 1 hour to row to a place and come back, how far is the place?

A) 2.9 km

B) 2.5 km

C) 3 km

D) 3.6 km

E) None of these

View Answer

Answer: option (A)

Explanation:

Speed downstream = (6 + 1) km/hr = 7 km/hr; Speed upstream = (6 -1) km/hr = 5 km/hr

Let the required distance be x km.

Then, x/7 + x/5 = 1 5x + 7x = 35 12x = 35 x = 2.9 km

15. A boat takes 20 hours for travelling downstream from point X to point Y and coming back to a point Z midway between X and Y. If the velocity of the stream is 4 km/hr and the speed of the boat in still water is 12 km/hr, what is the distance between X and Y?

A) 160 km

B) 180 km

C) 200 km

D) 220 km

E) None of these

View Answer

Answer: option (A)

Explanation:

Speed downstream = (12 + 4) km/hr = 16 km/hr

Speed upstream = (12 – 4) = 8 km/hr

Let the distance between X and Y be a km. Then,

a/16 + ((a/2))/8 = 20 a/16 + a/16 = 20 a/8 = 20 a = 160 km