A researcher believes that the percentage of people who exercise in California is greater than the national exercise rate. The national rate is 20%. The researcher gathers a random sample of 120 individuals who live in California and finds that the number who exercise regularly is 31 out of 120.

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?