To calculate the speed, you can use the formula:

$\text{Speed} = \frac{\text{Distance}}{\text{Time}}$

Given:

• Distance = 2 km
• Time = 0.5 hours (half an hour)

Now, substitute the values:

$\text{Speed} = \frac{2 \text{ km}}{0.5 \text{ hours}} = 4 \text{ km/h}$

So, the speed of the person is 4 kilometers per hour (km/h).

Let me know if you'd like more details or if you have any other questions! Here are 5 related questions for further exploration:

1. How do you convert km/h to meters per second?
2. How do you calculate the time it would take to walk a given distance at a specific speed?
3. What is the difference between average speed and instantaneous speed?
4. How can speed affect the energy consumption of walking?
5. What factors can affect a person's walking speed?

Tip: Always ensure that the units for distance and time are compatible when calculating speed!