Boats and Streams Quiz Set 002

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Question 1

The speed of a boat in still water is 84 km/h. It takes the same time to travel an upstream distance of 9 km as it takes to travel a downstream distance of 19 km. The rate of flow of the stream is?

 A

30 km/h.

 B

31 km/h.

 C

29 km/h.

 D

33 km/h.

Soln.
Ans: a

Let v km/h be the rate of flow of the stream. Upstream and downstream times are equal. So $9/{84 - v}$ = $19/{84 + v}$. Solving for v, or verifying by putting the given options one by one, we get v = 30 km/h.


Question 2

Two similar boats, A and B, start to move towards each other. If they meet when A has travelled $(1/8)$th of the distance, what is the ratio of the upstream speed to the downstream speed of a boat in that river?

 A

7.

 B

8.

 C

6.

 D

9.

Soln.
Ans: a

The boats are same, so they have the same speed in still water. Let the upstream speed be u and v be the downstream speed, and let the initial distance between them be L. When they meet they have travelled for the same time. So $(L/8)/u = ({7L}/8)/v$. The ratio $v/u$ = 7.


Question 3

The speed of a boat in still water is 10 km/h and rate of flow of the stream is 4 km/h. If it travels upstream for 5 hours, what is the distance travelled by the boat during the journey?

 A

30 km.

 B

31 km.

 C

29 km.

 D

33 km.

Soln.
Ans: a

The effective speed of the boat in the stream is 10 - 4 = 6 km/h. The distance is speed × time = 6 × 5 = 30 km.


Question 4

Two similar boats, A and B, start to move towards each other. If they meet when A has travelled $(1/5)$th of the distance, what is the ratio of the upstream speed to the downstream speed of a boat in that river?

 A

4.

 B

5.

 C

3.

 D

6.

Soln.
Ans: a

The boats are same, so they have the same speed in still water. Let the upstream speed be u and v be the downstream speed, and let the initial distance between them be L. When they meet they have travelled for the same time. So $(L/5)/u = ({4L}/5)/v$. The ratio $v/u$ = 4.


Question 5

The speed of a steamer in still water, the upstream speed of the steamer and the downstream speed of the steamer form an A.P.(Arithmetic Progression) whose common difference is $1{1/2}$. What is the speed of the river?

 A

$1{1/2}$ units.

 B

$2{1/2}$ units.

 C

$3{1/2}$ units.

 D

$2{1/4}$ units.

Soln.
Ans: a

Let the speed of the steamer in still water be u and the speed of the river be v. The three speeds are u - v, u and u + v. They are in an A.P. with a common difference equal to v. Since v is also the speed of the river, the required answer is: $1{1/2}$.


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This Blog Post/Article "Boats and Streams Quiz Set 002" 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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