An SRS of 40 San Diego County Schools graduates showed that 26 of the 40 enrolled in a college or university right out of high school.

a. Find a 90% confidence interval for the proportion of all San Diego County Schools graduates who enrolled in a college or university right out of high school. Be sure to justify the formula (assumptions/conditions).

b. The proportion for all graduates across the nation who enroll in a college or university right out of high school is 52%. Is there enough evidence at the 5% significance level to suggest that the proportion of San Diego County graduates is greater than the national average? Be sure to include all the parts of the test.