6.23 Consumption of sweet snacks. A recent study reported that the U.S. per capita consumption of sweet snacks among healthy weight children aged 12 to 19 years is 251.2 kilocalories per day (kcal/d).10 This was based on 24-hour dietary recall records of n = 2265 adolescents.

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    (a) Suppose that the population distribution is heavily skewed, with a standard deviation equal to 540 kcal/d. What is the margin of error for a 95% confidence interval of the per capita consumption of sweet snacks?

  2. (b) A future study is being planned and the goal is to have the margin of error no more than 15 kcal/d. Based on your answer to part (a), will this study require an examination of more or fewer recall records? Explain your answer without calculations.

  3. (c) Compute the sample size necessary for the study described in part (b).