Boats and Streams Quiz Set 004

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Question 1

An airplane can travel at 2 km/h in still air. But it takes thrice as much time to travel upstream as compared to the time it takes downstream, if air is blowing at a rate of R km/h. What is R?

 A

1 km/h.

 B

2 km/h.

 C

3 km/h.

 D

$1{1/3}$ km/h.

Soln.
Ans: a

If the distance travelled is D, we have $D/{2/1 - R}$ = 3 × $D/{2/1 + R}$. Cancelling D, and solving for R, we get R = 1 km/h.


Question 2

An airplane can travel at $1{5/9}$ km/h in still air. But it takes thrice as much time to travel upstream as compared to the time it takes downstream, if air is blowing at a rate of R km/h. What is R?

 A

${7/9}$ km/h.

 B

2 km/h.

 C

$2{3/11}$ km/h.

 D

$3{1/11}$ km/h.

Soln.
Ans: a

If the distance travelled is D, we have $D/{14/9 - R}$ = 3 × $D/{14/9 + R}$. Cancelling D, and solving for R, we get R = ${7/9}$ km/h.


Question 3

A boat can travel 192 km downstream in 12 hours. If it covers the same distance upstream in 32 hours, what is the rate of flow of the stream?

 A

5 kmph.

 B

6 kmph.

 C

4 kmph.

 D

8 kmph.

Soln.
Ans: a

The downstream speed = $192/12$ = 16 km/h, and the upstream speed = $192/32$ = 6 km/h. By the shortcut method, the speed of the stream is half of the difference between the downstream and upstream speeds of the boat. So the required speed = ${16 - 6}/2$ = 5 km/h.


Question 4

The speed of a boat in still water is 16 km/h and rate of flow of the stream is 6 km/h. If it travels upstream for 6 hours, what is the distance travelled by the boat during the journey?

 A

60 km.

 B

61 km.

 C

59 km.

 D

63 km.

Soln.
Ans: a

The effective speed of the boat in the stream is 16 - 6 = 10 km/h. The distance is speed × time = 10 × 6 = 60 km.


Question 5

A man can row a boat at the rate of 14 km/h in still water, and at the rate of 4 km/h against the stream. At what rate can he row down the stream?

 A

24 km/h.

 B

25 km/h.

 C

23 km/h.

 D

27 km/h.

Soln.
Ans: a

If v is the speed of the stream, 14 - v = 4, so the speed of the stream is 14 - 4 = 10 km/h. So his downstream speed would be 14 + 10 = 24 km/h.


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This Blog Post/Article "Boats and Streams Quiz Set 004" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2019-08-18.

Posted by Parveen(Hoven),
Aptitude Trainer


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