If an athlete runs at a speed of 12.9 km/hour, how long will it take the athlete to run a marathon (about 42.2 km)? Express your answer in hours using the correct number of significant figures. Do not enter your answer using scientific notation.

To determine how long it will take the athlete to run a marathon at a speed of 12.9 km/hour, we can use the following formula:

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

Here:
- The distance of the marathon is \( 42.2 \, \text{km} \),
- The speed of the athlete is \( 12.9 \, \text{km/hour} \).

Substituting the values:

\[
\text{Time} = \frac{42.2 \, \text{km}}{12.9 \, \text{km/hour}} = 3.2724806 \, \text{hours}
\]

Now, we round the result to the correct number of significant figures. Both the distance (42.2 km) and speed (12.9 km/h) have 3 significant figures, so the final answer should also be rounded to 3 significant figures.

Thus, the time it will take the athlete is:

\[
\text{Time} = 3.27 \, \text{hours}
\]

### Would you like more details or have any further questions?

Here are 5 related questions you might find interesting:
1. How long would it take the athlete to run 10 km at the same speed?
2. What would the athlete's speed need to be to complete the marathon in exactly 3 hours?
3. If the athlete's speed decreases by 10%, how much longer would it take to complete the marathon?
4. How far could the athlete run in 1 hour at this speed?
5. What is the speed in meters per second for this athlete?

Tip: When solving word problems, always ensure that units are consistent throughout the calculations.

Find out how long it takes to run a marathon (42.2 km) at a speed of 12.9 km/h. This problem covers key arithmetic concepts, including time calculation, unit conversion, and applying significant figures. Suitable for students in Grades 6-8.

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