Question

An accounting professor is notorious for being stingy in giving out good letter grades. In a large section of 160 students in the fall semester, she gave out only 3% A's, 18% B's, 47% C's, and 32% D's and F's. Assuming that this was a representative class, compute the 99% confidence interval of the probability of getting at least a B from this professor.

Answer 1

Total proportion of students of getting at least a B = 3% + 18% = 21% =0.21

Sample proportion = 0.21

Sample size (n) = 160

Confidence interval(in %) = 99

z @ 99% = 2.576

Since we know that

Required confidence interval = (0.21-0.0829, 0.21+0.0829)

Required confidence interval = (0.1271, 0.2929)

Please hit thumps up if the answer helped you.