1. Suppose that asthma affects 1 in 20 children in a population. You take a simple random sample of 300 children from this population.

a) Can we use the Normal approximation to the binomial in this instance? Show your calculations to support your answer.

b) What is the probability of seeing at least 25 cases in the sample? (Hint: Use the Normal approximation to the binomial. Do NOT use T-statistic).

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2. Suppose that the mean fasting cholesterol of teenage boys in the United States is = 175 mg/dL with = 50 mg/dL. A simple random sample of 39 boys whose fathers had a heart attack reveals a mean cholesterol of 195 mg/Dl.

Use a two-sided test and = 0.05 to determine whether the sample mean is significantly higher than expected. Remember to use and show all hypotheses testing steps.