Mary took her dog for a walk. They walked 3km in 40 minutes. What was their speed in kmh -1 ?

To calculate the speed, we use the formula:

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

Here, the distance is 3 km, and the time is 40 minutes. To convert the time into hours, since speed is required in km/h, we do the following:

\[
\text{Time in hours} = \frac{40 \text{ minutes}}{60 \text{ minutes/hour}} = \frac{2}{3} \text{ hours}
\]

Now, plug the values into the speed formula:

\[
\text{Speed} = \frac{3 \text{ km}}{\frac{2}{3} \text{ hours}} = 3 \times \frac{3}{2} = 4.5 \text{ km/h}
\]

So, Mary and her dog walked at a speed of **4.5 km/h**.

Would you like more details or have any questions?

Here are 8 related questions:
1. If Mary walked the same distance in 30 minutes, what would her speed be?
2. How long would it take Mary to walk 5 km at the same speed?
3. If Mary increased her speed to 6 km/h, how long would it take to walk 3 km?
4. What is the average speed if Mary walked 2 km in 20 minutes and then 1 km in 30 minutes?
5. How would the speed change if Mary took 1 hour to walk 3 km?
6. What distance would Mary cover in 1 hour at the same speed?
7. How would the speed change if Mary walked the same distance in 50 minutes?
8. What is the formula to convert speed from km/h to m/s?

**Tip:** When calculating speed, always ensure that the time is in hours if the speed is required in km/h.

Learn how to calculate Mary's walking speed when she walks 3km in 40 minutes. Understand the speed formula and how to convert time from minutes to hours. Suitable for students in Grades 5-7.

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