Answer:
The answer is below
Step-by-step explanation:
Given that:
Confidence interval (C) = 95%, mean (μ) = 85, standard deviation (σ) = 9, sample size (n) = 133
α = 1 - C = 1 - 0.95 = 0.05
α/2 = 0.025
The z score of α/2 (0.025) is the same as the z score of 0.475 (0.5 - 0.025) which is equal to 1.96.
The margin of error (E) is given as:
[tex]E=Z_\frac{\alpha}{2}*\frac{\sigma}{\sqrt{n} } \\\\E=1.96*\frac{9}{\sqrt{133} } \\\\E=1.53[/tex]
The confidence interval = (μ ± E) = (85 ±  1.53) = (83.47, 86.53)
The confidence interval is between 83.47 and 86.53.
