Answer:
The Confidence Interval = (66.1476, 68.8524)
Step-by-step explanation:
The formula for confidence interval of a normal distribution is given as:
Confidence Interval = μ ± z × σ/√n
Where:
μ is the mean height = 67.5
σ is the standard deviation = 2.1 inches
n is the number of samples = 16 bookcases
z = 99% confidence interval = 2.576
Confidence Interval = 67.5 ± 2.576 ×2.1√16
= 67.5 ± 2.576 × 2.1/4
Confidence Interval = 67.5 ± 1.3524
67.5 - 1.3524 = 68.8524
67.5 + 1.3524 = 66.1476
Therefore, the Confidence Interval = (66.1476, 68.8524)