The table below displays the number of school days missed in a previous month by a sample of 25 third graders.

No. of Days ........................ f
6 ......................................... 2
5 ......................................... 3
4 ......................................... 5
3 ......................................... 0
2 ......................................... 4
1 ......................................... 3
0 ......................................... 8
Total ................................. 25

a. Find the exact percentile rank for students who report missing 4 days.
b. Find the exact percentile rank for student who report missing 3 days.