An accounting professor is notorious for being stingy in giving
out good letter grades. In a large section of 220 students in the
fall semester, she gave out only 5% A's, 14% B's, 38% C's, and 43%
D's and F's. Assuming that this was a representative class, compute
the 85% confidence interval of the probability of getting at least
a B from this professor. (You may find it useful to
reference the z table. Round intermediate calculations to at
least 4 decimal places. Round "z" value and final answers
to 3 decimal places.)