If Mary walks at an average rate of 100 feet per minute around a quarter mile track, how many minutes will it take her to complete one lap?

To determine how long it takes Mary to complete one lap around the quarter-mile track, we first need to convert the distance of the track into feet. One mile is equal to 5,280 feet. Therefore, a quarter mile is:

[

\frac{5280}{4} = 1320 \text{ feet}

]

Now that we know the distance of the track is 1,320 feet, we can calculate the time it takes for Mary to complete one lap at her walking speed of 100 feet per minute. The time taken can be calculated using the formula:

[

\text{Time} = \frac{\text{Distance}}{\text{Rate}}

]

Substituting in the values we have:

[

\text{Time} = \frac{1320 \text{ feet}}{100 \text{ feet per minute}} = 13.2 \text{ minutes}

]

Since the question requires the number of minutes, we round 13.2 minutes to the nearest whole number, which is 13 minutes. This confirms that Mary will take approximately 13 minutes to walk one lap around the quarter-mile track.

Therefore, the correct answer is indeed the choice that states 13