Borrowers Bank classifies credit cardholders as "prime" whenever they pay interest charges for at least 6 of the last 12 billing cycles. The table below cross classifies 2080 cardholders according to whether they are 1) prime or not, and 2) below age 30 or not
Below 30 30 and Over
Prime 475 510
Not Prime 376 719
a) Construct a 95% confidence interval for the percentage of Prime cardholders among those who are less than 30 years old.
b) Construct a 95% confidence interval for the percentage of Prime cardholders among those who are 30 years or older.