Correct Answers: | |

Wrong Answers: | |

Unattempted: |

### Question 1

A boat travels a downstream distance of 84 km in 6 hours, and an upstream distance of 40 km in 4 hours. What is the speed of the stream?

**A**

2 kmph.

**B**

3 kmph.

**C**

4 kmph.

**D**

5 kmph.

**Soln.**

**Ans: a**

The downstream speed = $84/6$ = 14 km/h, and the upstream speed = $40/4$ = 10 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 = ${14 - 10}/2$ = 2 km/h.

### Question 2

The product of the downstream and upstream speeds of a boat in a river is 20. What is the difference between the squares of the speed of the boat in still water and the speed of the stream?

**A**

20.

**B**

22.

**C**

24.

**D**

28.

**Soln.**

**Ans: a**

Let the speed of the boat in still water be u, and let v be the speed of the stream. The product of the upstream and downstream speeds of the boat is $(u + v) × (u - v)$, which is $u^2 - v^2$, and, therefore, the required answer = 20.

### Question 3

If the speed of a boat in the direction of the stream current is 16 km/h, and the speed of the current is 4 km/h, what would be the speed of the boat against the current?

### Question 4

The upstream journey of a boat takes 6 times the time it takes it to complete the downstream journey. What is the ratio of the speed of the boat in still water to the speed of the stream?

**A**

$1{2/5}$.

**B**

3.

**C**

${2/7}$.

**D**

$3{1/7}$.

**Soln.**

**Ans: a**

Let the distance be L and the speed of the boat in still water be u, with v being the speed of the stream. We are given $L/{u - v} = 6 × L/{u + v}$. We can solve this equation for u/v to get u/v = ${6 + 1}/{6 - 1}$ = $1{2/5}$.

### Question 5

The speed of a boat in still water, the upstream speed of the boat and the downstream speed of the boat form an A.P.(Arithmetic Progression) whose middle term is ${5/8}$. What is the speed of the boat in still water?

**A**

${5/8}$ units.

**B**

$1{6/7}$ units.

**C**

$2{1/10}$ units.

**D**

$2{9/10}$ units.

**Soln.**

**Ans: a**

Let the speed of the boat in still water be u and the speed of the stream 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, and u as its middle term. Since u is also the speed of the boat in still water, the required answer is: ${5/8}$.

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This Blog Post/Article "Boats and Streams Quiz Set 019" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Updated on 2019-08-18.