Prepare for your exams

Study with the several resources on Docsity

Earn points to download

Earn points by helping other students or get them with a premium plan

Guidelines and tips

Prepare for your exams

Study with the several resources on Docsity

Earn points to download

Earn points by helping other students or get them with a premium plan

Community

Ask the community

Ask the community for help and clear up your study doubts

University Rankings

Discover the best universities in your country according to Docsity users

Free resources

Our save-the-student-ebooks!

Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors

MATH 225N Week 6 Confidence Intervals Questions And Answers Correctly Verified And RATED A+. Chamberlain College of Nursing

Typology: Exams

2022/2023

1 / 27

Download MATH 225N Week 6 Confidence Intervals Questions And Answers Correctly Verified And RATED A and more Exams Nursing in PDF only on Docsity! MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 1. On a busy Sunday morning, a waitress randomly sampled 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 MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 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. Mean 23.1043 Sample Standard Deviation 1.3693 Confidence Level n Mean StDev pop stdev SE t Margin of Error Lower Limit Upper Limit MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. Data 25.8 22.2 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 0.900 32 23.1043 1.3693 no 0.242060 1.696 0.410534 22.693766 23.514834 43 MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. Level n Mean StDev pop stdev SE z Margin of Error Lower Limit Upper Limit 12. Suppose heights, in inches of orangutans are normally distributed and have a known population standard deviation of 4 inches. A random sample of 16 orangutans is taken and gives a sample mean of 56 inches. Find the confidence interval of the population mean with a 95% confidence level. Lower limit = 54.04 and Upper Limit = 57.96 13. The population standard deviation for the total snowfalls per year in a city is 13 inches. If we want to be 95% confident that the sample mean is within 3 inches of the true population mean, what is the minimum sample size that should be taken? Answer: 73 snowfalls Minimum Sample Size μ for population mean Confidence Level StDev Error z-Value Minimum Sample Size 14. The population standard deviation for the body weights for employees of a company is 10 pounds. If we want to be 95% confident that the sample mean is within 3 pounds of the true population mean, what is the minimum sample size that should be taken. Answer: 43 employees Minimum Sample Size μ for population mean Confidence Level StDev Error z-Value MATH 225N Week 6 Confidence Inte tions And Answers 100% Correctly Verified And RATED A+. Chamberlain College of Nursing MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 49 251.7755 37.0000 yes 5.285714 1.960 10.360000 241.415500 262.135500 0.950 13 3 1.960 73 0.950 10 3 1.960 rvals Ques If sampl percenta MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. Minimum Sample Size 15. The length, in words, of the essays written for a contest are normally distributed with a population standard deviation of 442 words and an unknown population mean. If random sample of 24 essays is taken and results in a sample mean of 1330 words, find a 99% confidence interval for the population mean. Round to two decimal places. Answer: Lower limit = 1097.59 upper Limit = 1562.41 16. Brenda wants to estimate the percentage of people who eat fast food at least once per week. She wants to create a 95% Confidence interval which has an error bound of at most 2%. How many people should be polled to create the confidence interval? Answer: 2401 Minimum Sample Size p for Proportion Confidence Level Sample Proportion Error Enter decimal e proportion unknown enter 0.5 Write ge as decimal MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 0.95 0 0.5 0.02 6 Confidenceberla n 2401 1.96 0 MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. z-Value Minimum Sample Size 17. Suppose a clothing store wants to determine the current percentage of customers who are over the age of forty How many customers should the company survey in order to be 92% confident that the estimated (sample) proportion is within 5% of the true population proportion of customers who are over the age of 40? Answer: 307 Minimum Sample Size p for Proportion Confidence Level 0.920 Enter decimal Sample Proportion 0.5 If sample proportion unknown enter 0.5 Error 0.05 Write percentage as decimal z-Value 1.751 Minimum Sample Size 307 18. Suppose the scores of a standardized test are normally distributed. If the population standard deviation is 2 points, what minimum sample size is needed to be 90% confident that the sample mean is within 1 point of the true population mean? Be sure to round up to the nearest integer. Provide your answer below: 11 Minimum Sample Size μ for population mean Confidence Level StDev Error z-Value Minimum Sample Size 19. The number of square feet per house are normally distributed with a population standard deviation of 197 square feet and an unknown population mean. If a random sample of 25 houses is taken and results in a sample mean of 1820 square feet, find a 99% confidence interval for the population mean. Round to 2 decimal places. Answer: 1718.51 – 1921.49 t or z Confidence Interval for µ nd MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 0.900 2 1 1.645 11 Confidence Level n Mean StDev pop 0.990 25 1,820.0000 MATH 225N Week 197.0000 Intervals Questions And Answers 100% Correctly Verified A RATED A+. Cham yes ge of Nursing g time for c nation periods, MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. deviation of 7 miles per hour and an unknown population mean. If a random sample of 20 vehicles is taken and results in a sample mean of 60miles per hour, find a 98% confidence interval for the population mean. • Round the final answer to two decimal places. Answer 56.36 – 63.64 t or z Confidence Interval for µ Confidence Level n Mean StDev pop stdev SE z Margin of Error Lower Limit Upper Limit 25. Suppose finishin clists in a race are normally distributed and have a known population standard deviation of 6minutes and an unknown population mean. A random sample of 18 cyclists is taken and gives a sample mean of 146minutes. Find the confidence interval for the population mean with a 99% confidence level. Answer: 142.36 – 149.64 t or z Confidence Interval for µ Confidence Level n Mean StDev pop stdev SE z Margin of Error Lower Limit Upper Limit 26. Suppose the germi in days, for grass seed are normally distributed. If the population standard deviation is 3days, what minimum sample size is needed to be 90% confident that the sample mean is within 1 day of the true population mean? MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 0.980 20 60.0000 7.0000 yes 1.565248 2.326 3.640766 56.359234 y63.640766 0.990 18 146.0000 6.0000 yes 1.414214 2.576 3.643014 142.356986 149.643014 Confide rlain MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. Answer: 25 seeds Minimum Sample Size μ for population mean Confidence Level StDev Error z-Value Minimum Sample Size Suppose the number of square feet per house is normally distribute If the population standard deviation is 155 square feet, what minimum sample size is needed to be 90% confident that the sample mean is within 47 square feet of the true population mean? Answer: 30 houses Minimum Sample Size μ for population mean Confidence Level StDev Error z-Value Minimum Sample Size 27. In a survey of 1,000 adults in a country, 722 said that they had eaten fast food at least once in the past month. Create a 95% confidence interval for the population proportion of adults who ate fast food at least once in the past month. Use Excel to create the confidence interval, rounding to four decimal places. Answer: 0.6942 – 0.7498 Confidence Interval for p Proportions Confidence Level n Number of Successes Sample Proportion SE z MATH 225N Week 6 RATED A+. Chambe MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 0.900 3 1 1.645 25 0.900 155 47 1.645 30 0.950 1000 722 0.722000 0.014167 1.960 0.027768 0.694232 nc 0.749768 o MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. e Intervals Questions And Answers 100% Correctly Verified And llege of Nursing MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 59.003 58.992 58.926 59.032 58.958 59.093 58.955 59.003 58.952 59.057 59.056 59.074 59.128 59.001 59.007 t or z Confidence Interval for µ Confidence Level n Mean StDev pop stdev SE t Margin of Error Lower Limit Upper Limit 30. A tax assessor wants to assess the mean property tax bill for all homeowners in a certain state. From a survey ten years ago, a sample of 28 property tax bills is given below. Assume the property tax bills are approximately normally distributed. Use Excel to construct a 95% confidence interval for the population mean property tax bill. Round your answers to two decimal places and use increasing order. MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 0.950 24 59.0050 0.0494 no 0.010084 2.069 0.020863 58.984137 59.025863 no n exams in sta MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. Answer: 1185.91 – 1595.59 31. The table below provides a random sample of 20 exam scores for a large geology class. Use Excel to construct a 90% confidence interval for the mean exam score of the class. Round your answers to one decimal place and use ascending order. Answer: 79.7 – 88.5 t or z Confidence Interval for µ Confidence Level n Mean StDev pop stdev SE t Margin of Error Lower Limit Upper Limit 32. Suppose scores o sample of 26 scores i tistics are normally distributed with an unknown population mean. A . Use Excel to find a 90% confidence interval for the true mean of statistics exam scores. Round your answers to one decimal place and use increasing order. Answer: 67.2 – 69.4 Confidence Level n Mean StDev pop stdev SE t Margin of Error Lower Limit Upper Limit 33. In a city, 22 coffee shops are randomly selected, and the temperature of the coffee sold at each shop is noted. Use Excel to find the 90% confidence interval for the population mean temperature. Assume the temperatures are approximately normally distributed. Round your answers to two decimal places and use increasing order. MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 0.900 20 84.1000 11.4200 2.553590 1.729 4.415156 79.684844 s g 8 i 8 v .5 e 1 n 51 b 5 0.900 26 68.3077 3.2220 no 0.631886 1.708 1.079262 67.228438 69.386962 MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. Answer: 153.21 – 161.43 t or z Confidence Interval for µ Confidence Level n Mean StDev pop stdev SE t Margin of Error Lower Limit Upper Limit 34. Weights, in pounds, of ten-year-old girls are collected from a neighborhood. A sample of 26 is given below. Assuming normality, use Excel to find the 98% confidence interval for the population mean weight μ. Round your answers to three decimal places and use increasing order. Answer: 66.497 – 77.234 t or z Confidence Interval for µ Confidence Level n Mean StDev pop stdev SE t Margin of Error Lower Limit Upper Limit 35. A sample of 22 te d for number of times they can be heated on a Bunsen burner before they crack is given below. Assume the counts are normally distributed. Use Excel to construct a 99% confidence interval for μ. Round your answers to two decimal places and use increasing order. Answer: 1071.77 – 1477.33 MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 161.429668 0.900 22 157.3182 11.2054 no 2.388999 1.721 4.111468 153.206732 0.980 26 71.8654 11.0160 no 2.160415 2.485 5.368632 st- t 6 u 6 b .4 e 9 s 67 te68 ste Confidence rlain MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 42. A large company is concerned about the commute times of its employees. 333 employees were surveyed, and 131employees said that they had a daily commute longer than 30 minutes. Create a 95% confidence interval for the proportion of employees who have a daily commute longer than 30 minutes. Use Excel to create the confidence interval, rounding to four decimal places. Provide your answer below: .3409 - .4459 Confidence Interval for p Proportions Confidence Level n Number of Successes Sample Proportion SE z Margin of Error Lower Limit Upper Limit 43. The following data represent a random sample for the ages of 41 players in a baseball league. Assume that the population is normally distributed with a standard deviation of 2.1 years. Use Excel to find the 98% confidence interval for the true mean age of players in this league. Round your answers to three decimal places and use ascending order. Answer: 27.579 – 29.104 t or z Confidence Interval for µ Confidence Level n Mean StDev pop stdev SE z Margin of MATH 225N Week 6 RATED A+. Chambe Intervals Questions And Answers 100% Correctly Verified And ge of Nursing MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 0.950 333 131 0.393393 0.026770 1.960 0.052469 0.340925 0.445862 0.980 41 28.3415 2.1000 yes 0.327965 2.326 0.762846 27.578654 29.104346 MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. Error Lower Limit Upper Limit 44. In order to determine the average weight of carry-on luggage by passengers in airplanes, a sample of 25 pieces of carry-on luggage was collected and weighed in pounds. Assume that the population is normally distributed with a standard deviation of 5 pounds. Find the 95% confidence interval of the mean weight in pounds. Round your answers to two decimal places and use ascending order. Answer: 15.36 – 19.28 MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. o determine 7 ours worked pe MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. t or z Confidence Interval for µ Confidence Level n Mean StDev pop stdev SE z Margin of Error Lower Limit Upper Limit 45. A company wants t confidence interval for the average CPU time of its teleprocessing transactions. A sample m transactions in milliseconds is given below. Assume that the transaction times follow a normal distribution with a standard deviation of 600 milliseconds. Use Excel to determine a 98% confidence interval for the average CPU time in milliseconds. Round your answers to the nearest integer and use ascending order. Answer: 5907 – 6240 t or z Confidence Interval for µ Confidence Level n Mean StDev pop stdev SE z Margin of Error Lower Limit Upper Limit 46. The number of h year per adult in a state is normally distributed with a standard deviation of 37. A sample of 115 adults is selected at random, and the number of hours worked per year per adult is given below. Use Excel to calculate the 98% confidence interval for the mean hours worked per year for adults in this state. Round your answers to two decimal places and use ascending order. Answer: 2090.03 – 2106.09 47. An automobile shop manager timed 27 employees and recorded the time, in minutes, it took them to change a water pump. Assuming normality, use Excel to find the 99% confidence interval for the true mean. MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 0.950 25 17.3200 5.0000 yes 1.000000 1.960 1.960000 15.360000 a of 19.280 r 0 a 0 n 0 do 0.980 70 6,073.4286 600.0000 yes 71.713717 2.326 166.806105 5906.622495 6240.234705 r 601 1.96 0 307 1.75 1 MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. Minimum Sample Size p for Proportion Confidence Level Sample Proportion Error z-Value Minimum Sample Size 53. Suppose a clothing store wants to determine the current percentage of customers who are over the age of forty. How many customers should the company survey in order to be 92% confident that the estimated (sample) proportion is within 5percentage points of the true population proportion of customers who are over the age of forty? Answer: 307 Minimum Sample Size p for Proportion Confidence Level Sample Proportion Error z-Value Minimum Sample Size 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. MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 0.95 0 0.5 0.04 0.92 0 0.5 0.05 MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 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 MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+. 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) MATH 225N|Week 6- Confidence Intervals Chamberlain College of Nursing Questions And Answers RATED A+.