Answer: 2.5 or 2 1/2
Explanation:
You can convert the mixed fractions to decimal numbers:
- Divide the numerator by the denominator of the fraction.
- Add the result to the whole number.
Thenyou have:
Barbara's time:

Donna's time:

Cindy's time:

Nicole's time:

As you can see, the fastest girl is Cindy and the slowest girl is Nicole.
Then, you must make the following subtraction to calculate the difference:
or 2 1/2