In a survey, 13 people were asked how much they spent on their child's last birthday gift. The results were roughly bell

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In A Survey 13 People Were Asked How Much They Spent On Their Child S Last Birthday Gift The Results Were Roughly Bell 1 (58.18 KiB) Viewed 33 times

In A Survey 13 People Were Asked How Much They Spent On Their Child S Last Birthday Gift The Results Were Roughly Bell 2 (197.39 KiB) Viewed 33 times

In a survey, 13 people were asked how much they spent on their child's last birthday gift. The results were roughly bellshaped with a mean of $42 and standard deviation of $2. Find the margin of error at a 80% confidence level. Give your answer to two decimal places.
A researcher is interested in finding a 98% confidence interval for the mean number minutes students are concentrating on their professor during a one hour statistics lecture. The study included 127 students who averaged 32.6 minutes concentrating on their professor during the hour lecture. The standard deviation was 11.2 minutes. Round answers to 3 decimal places where possible. a. To compute the confidence interval use a distribution. b. With 98% confidence the population mean minutes of concentration is between and minutes. c. If many groups of 127 randomly selected members are studied, then a different confidence interval would be produced from each group. About percent of these confidence intervals will contain the true population mean minutes of concentration and about percent will not contain the true population mean minutes of concentration.