1.Assume that a sample is used to estimate a population proportionp. Find the 80% confidence interval for a sample of size 147 with 74 successes. Enter your answer as anopen-interval(i.e., parentheses) using decimals (not percents) accurate to three decimal places.

80% C.I. =

Answer should be obtained without any preliminary rounding. However, the critical value may be rounded to 3 decimal places.

2.Out of 300 people sampled, 21 had kids. Based on this, construct a 95% confidence interval for the true population proportion of people with kids.

Give your answers as decimals, to three places

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3.In a survey, 22 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $41 and standard deviation of $3. Find the margin of error at a 98% confidence level.

Give your answer to two decimal places.

4.You measure 23 textbooks' weights, and find they have a mean weight of 54 ounces. Assume the population standard deviation is 10.4 ounces. Based on this, construct a 99% confidence interval for the true population mean textbook weight.

Give your answers as decimals, to two places