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```1)Speed of boat in still water is 20 km/hr. If the speed of the stream is 8 km/hr, find its downstream and upstream speeds ?

A)20,5

B)20,12

C)28,12

D)18,10

**Answer:**C)28,12

**Explanation:**
Here

u=20

v=8

Downstream Speed = u + v = 20 + 8 = 28 km/hr

Upstream Speed = u - v = 20 -8 = 12 km/hr

```
```2) A man can row downstream at 24 km/hr and upstream at 16 km/hr. Find his speed in still water and the rate of the current.

A)20,4

B)20,2

C)15,3

D)16,4

**Answer:**A)20,4

**Explanation:**
Speed of the boat or swimmer in still water

= 1/2 * (Downstream Speed + Upstream Speed)

= 1/2 * (24+16)

= 20 km/hr

Speed of the current

= 1/2 * (Downstream Speed - Upstream Speed)

= 1/2 * (24-16)

= 4 km/hr

```
```3) The speed of the boat in still water is 18 km/hr. It takes twice as long as to go upstream to a point as to return downstream to the starting point. What is the speed of the current?

A)4 km/hr

B)3 km/hr

C)6 km/hr

D)4 km/hr

**Answer:**C)6 km/hr

**Explanation:**
Let speed of the current = x km/hr.

As per question,

Downstream Speed = 2*Upstream speed

18 + S = 2(18 - S)

S = 6 km/hr

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```4) A boat can travel with a speed of 15 km/hr in still water. If the speed of the stream is 9 km/hr, find the time taken by the boat to go 72 km downstream.

A)2 hours

B)3 hours

C)4 hours

D)5 hours

**Answer:**B)3 hours

**Explanation:**
Speed downstream

= (15 + 9) km/hr

= 24 km/hr.

Time taken to travel 68 km downstream

= 72/24 hrs

= 3 hrs.

```
```5)In one hour, a boat goes 16 km/hr along the stream and 10 km/hr against the stream. The speed of the boat in still water (in km/hr) is:

**Answer:**13 kmph.

**Explanation:**
Speed in still water = 1/2(16+10) kmph

= 13 kmph.