Answer:
There are 50 part-time students:
15 of them, take only one course.
10 of them, take only two courses.
then the rest, this is:
50 - 10 - 15 = 25
25 students take 3 courses.
b) What percent of students take exactly two courses?
15 out of 50 take exactly two courses, the percentage is:
p = (10/50)*100% = 20%.
c) What percent of students take one or two courses?
This will be the percentage of students that take only one course plus the percentage of students that take two courses:
The percentage of students that take two courses is already known: 20%.
Now, for 1 course we have 15 students out of 50, the percentage is:
p = (15/50)*100% = 30%.
Then the percentage that take 1 or 2 courses is:
P = 30% + 20% = 50%