The manager of a large manufacturing company wants to estimate the proportion of items that have been manufactured with defects. How many items are required for a random sample to obtain a margin of error of at most 0.04 with 90% confidence?Find the z-table here.

When the defect proportion is unknown, use p = 0.5 to ensure the sample size is large enough. For 90% confidence, z* = 1.645, so n = (1.645² × 0.5 × 0.5) / 0.04² ≈ 422.8. Round up to 423 items, so the correct choice is 423.

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