Excel Exercise: The One-Input Data Table

The formula can be rewritten as: N = (zα S / E ) 2 . where E is the “margin of error” (half the width, W). As an approximation, for 95% confidence, use the value of 2 for zα (instead of 1.96) – remember that this is an approximation, after all! Then the formula is a very concise and easily remembered: N = (2S / E ) 2 ................
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