A boat can travel with a speed of 30 km/hr in still water. If the speed of the stream is 6 km/hr, find the time taken by the boat to go 108 km downstream.

Options

A. 2 hrs
B. 5 hrs
C. 3 hrs
D. 4 hrs

Explanation

To solve the problem of finding the time taken by the boat to go 108 km downstream, we can follow these steps:

### Step 1: Determine the speed of the boat downstream.
The speed of the boat in still water is 30 km/hr, and the speed of the stream is 6 km/hr. When the boat is going downstream, the speeds add up.

\[ \text{Speed downstream} = \text{Speed of boat} + \text{Speed of stream} \]
\[ \text{Speed downstream} = 30 \text{ km/hr} + 6 \text{ km/hr} = 36 \text{ km/hr} \]

### Step 2: Use the formula for distance to find time.
The formula for distance is given by:

\[ \text{Distance} = \text{Speed} \times \text{Time} \]

We can rearrange this formula to find time:

\[ \text{Time} = \frac{\text{Distance}}{\text{Speed}} \]

### Step 3: Substitute the values into the formula.
We know the distance is 108 km and the speed downstream is 36 km/hr.

\[ \text{Time} = \frac{108 \text{ km}}{36 \text{ km/hr}} \]

### Step 4: Calculate the time.
\[ \text{Time} = 3 \text{ hours} \]

### Final Answer:
The time taken by the boat to go 108 km downstream is **3 hours**.

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