math
posted by Jasmine .
Weekly mileage totals 24 runners
10 15 20 25 30 35 40 45 50 55 60
Max 55 Min 15 Q1 20 Q2 35 Q3 40
1 What percent of runners run less than 40 miles a week?
2 How many runners run less than 20 miles a week

First, 10 is your minimum (the least)rather than 12, and 60 is your maximum (the most).
1. Q3 = 75th percentile
2. Q1 = 25th percentile
Q2 = 50th percentile or the median.
This is assuming that your quartile values are correct.
I hope this helps. Thanks for asking.