Exercise 1: A 95% Confidence Interval for n=16 — Possible Solution
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GIVEN
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n = 16, sample mean = 550, sigma = 48

STEP 1: THE STANDARD ERROR
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SE = sigma / sqrt(n) = 48 / sqrt(16) = 48 / 4 = 12

STEP 2: THE 95% CONFIDENCE INTERVAL
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Per this chapter's own formula, using z* = 1.96 for 95% confidence:

  margin = z* x SE = 1.96 x 12 = 23.52

  CI = 550 +/- 23.52 = [526.48, 573.52]

WHY THIS WORKS AS AN ANSWER
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The standard error is computed first using Chapter 2's own formula,
and the confidence interval is built directly on top of it using this
chapter's own point-estimate +/- (critical value x SE) formula with
the correct 95% critical value.