A boy crosses a 300 metres wide road in 30 seconds. What is his speed (in km/hr)?

Options

A. 18
B. 54
C. 36
D. 27

Answer

To find the speed of the boy in kilometers per hour, we can follow these steps:

### Step 1: Identify the distance and time
The boy crosses a road that is 300 meters wide in 30 seconds.

### Step 2: Use the formula for speed
The formula for speed is given by:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]

### Step 3: Substitute the values into the formula
Here, the distance is 300 meters and the time is 30 seconds. So we can substitute these values:
\[ \text{Speed} = \frac{300 \text{ meters}}{30 \text{ seconds}} = 10 \text{ meters per second} \]

### Step 4: Convert the speed from meters per second to kilometers per hour
To convert meters per second to kilometers per hour, we use the conversion factor \( \frac{18}{5} \):
\[ \text{Speed in km/hr} = 10 \text{ m/s} \times \frac{18}{5} \]

### Step 5: Calculate the speed in kilometers per hour
Now, we perform the multiplication:
\[ \text{Speed in km/hr} = 10 \times \frac{18}{5} = 10 \times 3.6 = 36 \text{ km/hr} \]

### Final Answer
The speed of the boy is **36 kilometers per hour**.

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