Answer:
The answer is below
Explanation:
Given that:
mean (μ) = $212.45, standard deviation (σ) = $38.92 and sample size (n) = 20 students.
a) Confidence (C) = 99% = 0.99
α = 1 - C = 1 - 0.99 = 0.01
α/2 = 0.01/2 = 0.005
The z score of α/2 is the same as the z score of 0.495 (0.5 - 0.005) which is equal to 2.576. This means that Z(α/2) = 2.576
The margin of error (E) is given as:

The confidence interval = (μ ± E) = (212.45 ± 8.7) = (203.75, 221.15)
Hence the 99% confidence interval is between 203.75 and 221.15.
b) The population mean is the same as the sample mean. Hence the population mean = $212.45