Final answer:
The percentage of February that Mary spends practicing swimming is calculated as (20/28) × 100%, which is approximately 71%. However, the closest answer from the choices given is 70%.
Step-by-step explanation:
The question asks us to calculate what percentage of the month of February Mary has swim practice if she practices 20 out of 28 days. To find this percentage, we use the formula for calculating the percentage of a part relative to the whole, which is Percentage = (Part/Whole) × 100%. In this case, the 'part' is the 20 days of swim practice, and the 'whole' is the 28 days of February. Performing the calculation gives us: (20/28) × 100% = 71.42857%. When rounded to the nearest whole number, this is approximately 71%, which means the correct answer is not listed in the provided options.
However, if Mary indeed has swim practice for 20 out of 28 days and we need to choose the closest option from the given answers, it would be (b) 70%. To find the percent of the month of February that Mary has swim practice, we divide the number of days she has swim practice by the total number of days in February and multiply by 100. The number of days Mary has swim practice is 20. The total number of days in February is 28. Percentage of the month of February that Mary has swim practice = (20/28) x 100% = 71.43%