A boy walks 800m in 20 minutes. Calculate his average speed in Km/H

1. Analyze the question

We are given the distance in meters (m) and the time in minutes (min). We need to calculate the average speed, but the final answer must be in kilometers per hour (km/h).

2. Explain the concept

The formula for speed is:

To get the answer in km/h, we must ensure:

• Distance is in kilometers (km): Since $1000\text{m} = 1\text{km}$, we divide the distance in meters by 1000.
• Time is in hours (h): Since $60\text{min} = 1\text{hour}$, we divide the time in minutes by 60.

3. Show the solution

Step 1: Convert distance to kilometers

Step 2: Convert time to hours

Step 3: Calculate speed

4. Identify the answer

Comparing our result to the given options, the correct choice is A.

5. Tip

When converting units, always check the required units first. If you are converting from m/min to km/h, you can use the conversion factor: multiply by 60 and divide by 1000 (or simply multiply by 0.06). $800 \times 0.06 = 48$; then $48 / 20 = 2.4$. This is a quick way to verify your work during the exam!