A teacher believes that the percentage of students at her high school who go on to college is higher than the rate in the general population of high school students. The rate in the general population is 30%. In the most recent graduating class at her high school, the teacher found that 90 students graduated and that 40 of those went on to college.

a. What is χ²_obt?

b. What is df for this test?

c. What is χ²_cv?

d. What conclusion should be drawn from these results?