MATH 225 Week 6 Confidence Intervals Questions and answers (2020) – Chamberlain College of Nursing | MATH225 Week 6 Confidence Intervals Questions and answers (2020)

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MATH 225 Week 6 Confidence Intervals Questions and answers (2020) – Chamberlain College of Nursing Week 6 Questions on Confidence Intervals 1. On a busy Sunday morning, a waitress randomly sam... pled customers about their preference for morning beverages, Specifically, she wanted to find out how many people preferred coffee over tea. The proportion of customers that preferred coffee was 0.42 with a margin of error 0.07. Construct a confidence interval for the proportion of customers that preferred coffee. (0.42 - 0.07), (0.42 + 0.07) = (0.35), (0.49) 2. A company sells juice in 1quart bottles. In a quality control test, the company found the mean volume of juice in a random sample of bottles was X = 31 ounces, with a marginal error of 3 ounces. Construct a confidence interval for the mean number of ounces of juice bottled by this company. (31-3), 31+3) = (28), (34) 3. Randomly selected employees at an office were asked to take part in a survey about overtime. The office manager wanted to find out how many employees worked overtime in the last week. The proportion of employees that worked overtime was 0.83, with a margin of error of 0.11. (0.83 – 0.11), (0.83 + 0.11) = (0.72), (0.94) 4. A random sample or garter snakes were measured, and the proportion of snakes that were longer than 20 inches in length recorded. The measurements resulted in a sample proportion of p = 0.25 with a sampling standard deviation of Op = 0.05. Write a 68% confidence interval for the true proportion of garter snakes that were over 20 inches in length. (.25 - .05). (.25 + .05) = (0.20), (.30) 5. The average number of onions needed to make French onion soup from the population of recipes is unknown. A random sample of recipes yields a sample mean of x = 8.2 onions. Assume the sampling distribution of the mean has a standard deviation of 2.3 onions. Use the Empirical Rule to construct a 95% confidence interval for the true population mean number of onions. Since 95% falls in 2 SD’s the calculation would be (8.2 – 4.6) “4.6 is the margin of error”, (8.2 + 4.6) = (3.6) , (12.8) 6. In a survey, a random sample of adults were asked whether a tomato is a fruit or vegetable. The survey resulted in a sample proportion of 0.58 with a sampling standard deviation of 0.08 who stated a tomato is a fruit. Write a 99.7 confidence interval for the true proportion of number of adults who stated the tomato is a fruit. (0.58 – 3 x 0.08), (0.58 + 3 x 0.08) =(0.58 – .24), (0.58 + .24) = 0.34 + 0.82 7. A college admissions director wishes to estimate the mean number of students currently enrolled. The age of random sample of 23 students is given below. Assume the ages are approximately normally distributed. Use Excel to construct a 90% confidence interval for the population mean age. Round your answer to 2 decimal places and use increasing order. Use week 6 worksheet to get mean and SD. Data 25.8 Mean 23.1043 22.2 Sample Standard Deviation 1.3693 22.5 22.8 24.6 24 22.6 23.6 22.8 23.1 21.5 21.4 22.5 24.5 21.5 22.5 20.5 23 25.1 25.2 23.8 21.8 24.1 Confidence Level 0.900 n 32 Mean 23.1043 StDev 1.3693 pop stdev no SE 0.242060 t 1.696 Margin of Error 0.410534 Lower Limit 22.693766 Upper Limit 23.514834 Lower margin of error = 22.69 and upper limit is 23.51 8. Suppose that the scores of bowlers in a particular league follow a normal distribution such that a standard deviation of the population is 12. Find the 95% confidence interval of the mean score for all bowlers in this league using the accompanying data set of 40 random scores. Round your answers to 2 decimal places using ascending order. Lower Limit = 90.78 Upper Limit = 98.22 Confidence Level 0.950 n 40 Mean 94.5000 StDev 12.0000 pop stdev yes SE 1.897367 z 1.960 Margin of Error 3.718839 Lower Limit 90.781161 Upper Limit 98.218839 9. In the survey of 603 adults, 98 said that they regularly lie to people conducting surveys. Create a 99% confidence interval for the proportion of adults who regularly lie to people conducting surveys. Use excel to create the confidence interval rounding to 4 decimal places. -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 54. The average height of a population is unknown. A random sample from the population yields a sample mean of x¯=66.3inches. Assume the sampling distribution of the mean has a standard deviation of σx¯=0.8 inches. Use the Empirical Rule to construct a 95% confidence interval for the true population mean height. Provide your answer below: 64.7 – 67.9 55. In a random sample of 30 young bears, the average weight at the age of breeding is 312 pounds. Assuming the population ages are normally distributed with a population standard deviation is 30 pounds, use the Empirical Rule to construct a 68%confidence interval for the population average of young bears at the age of breeding. Do not round intermediate calculations. Round only the final answer to the nearest pound. Remember to enter the smaller value first, then the larger number. Answer: 307 – 317 56. In a food questionnaire, a random sample of teenagers were asked whether they like pineapple pizza. The questionnaire resulted in a sample proportion of p′=0.43, with a sampling standard deviation of σp′=0.06, who like this type of pizza. Write a 99.7% confidence interval using the Empirical Rule for the true proportion of teenagers who like pineapple pizza. Answer: 0.25 - 0.61 57. A marine biologist is interested in whether the Chinook salmon, a particular species of salmon in the Pacific Northwest, are getting smaller within the last decade. In a random sample of this species of salmon, she found the mean length was x¯=36inches with a margin of error of 9 inches.  Construct a confidence interval for the mean length of Chinook salmon. Answer: 27 - 45 58. A researcher is trying to estimate the population mean for a certain set of data. The sample mean is 45, and the error bound for the mean is 9, at a 99.7% confidence level. (So, x¯=45 and EBM = 9.) Find and interpret the confidence interval estimate. Answer: We can estimate, with 99.7% confidence that the true value of the population mean is between 36 and 54. 59. A random sample of registered voters were asked about an issue on the ballot of an upcoming election. The proportion of those surveyed who plan to vote "Yes" on the issue is 0.54, with a margin of error of 0.06. Construct a confidence interval for the proportion of registered voters that plan to vote "Yes" on the issue. Answer: .48 - .60 (0.54-0.06 ; 0.54 + 0.06) [Show More]

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