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Question 1 4 points Save A study of 200 apple trees showed that the average number of apples per tree was 500. The standard deviation of the population is 200. Which of the following is the 98% confidence interval for the mean number of apples for all trees? (472.3, 527.7) (467.1, 532.9) (463.8, 536.2) (463.6, 536.4)

Question 2 4 points Save A study of 50 white mice showed that their average weight was 6.2 ounces. The standard deviation of the population is 0.4 ounces. Which of the following is the 90% confidence interval for the mean weight per white mouse? (6.11, 6.29) (5.98, 6.42) (6.09, 6.31) (5.54, 6.86)

Question 3 4 points Save A study of 90 bolts of carpet showed that their average length was 200 yards. The standard deviation of the population is 6 yards. Which of the following is the 95% confidence interval for the mean length per bolt of carpet? (198.96, 201.04) (197.06, 202.94) (198.53, 201.47) (198.76, 201.24)

Question 4 4 points Save If a population has standard deviation 14, what is the minimum sample size to be 95% confident that the error should be accurate to within 5? 61

6 31 12 Question 5 4 points Save A researcher conducted a study of the access speed of 30 hard drives and concluded that his maximum error of estimate was 20. If he were to conduct a second study to reduce the maximum error of estimate to 4, about how many hard drives should he include in his new sample?

30 60 150 750

Question 6 4 points Save A study of peach trees showed that the average number of peaches per tree was 500. The standard deviation of the population is 200. A scientist wishes to find the 95% confidence interval for the mean number of peaches per tree. How many trees does she need to sample to be accurate within 14 peaches per tree? 205 553 658 784

Question 7 4 points Save A study of elephants wishes to determine the average weight of a certain subspecies of elephants. The standard deviation of the population is 1500 pounds. How many elephants need to be weighed so find we can be 90% confident to be accurate within 350 pounds?

50 60 71 166

Question 8 4 points Save A previous study of nickels showed that the standard deviation of the weight of nickels is 200 milligrams. A coin counter manufacturer wishes to find the 80% confidence interval for the average weight of a nickel. How many nickels does he need to weigh to be accurate within 10 milligrams? 400 657 1083 284

Question 9 4 points Save A previous analysis of paper boxes showed that the standard deviation of their lengths is 7 millimeters. A packer wishes to find the 99% confidence interval for the average length of a box. How many boxes does he need to measure to be accurate within 4 millimeters?

4 30 21 17

Question 10 4 points Save In a study of size 8 where the variance is unknown, the distribution that should be used to calculate confidence intervals is a normal distribution

a t distribution with 7 degrees of freedom a t distribution with 8 degrees of freedom a t distribution with 9 degrees of freedom

Question 11 4 points Save A food snack manufacturer samples 13 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 9.8 and the sample standard deviation is 0.15, find the 95% confidence interval of the true mean. (9.76, 9.84) (9.47, 10.13) (9.72, 9.88) (9.71, 9.89)

Question 12 4 points Save 8 squirrels were found to have an average weight of 9.8 ounces with a sample standard deviation is 0.10. Find the 95% confidence interval of the true mean weight. (9.69, 9.91) (9.48, 10.12) (9.71, 9.89) (9.76, 9.84)

Question 13 4 points Save The winning team's scores in 7 high school basketball games were recorded. If the sample mean is 10.2 points and the sample standard deviation is 0.25 points, find the 98% confidence interval of the true mean. (10.11, 10.29) (9.90, 10.50) (9.98, 10.42) (9.61, 10.79)

Question 14 4 points Save A recent study of 750 Internet users in Europe found that 35% of Internet users were women. What is the 95% confidence interval of the true proportion of women in Europe who use the Internet? 0.321

Question 15 4 points Save A survey of 800 women shoppers found that 17% of them shop on impulse. What is the 98% confidence interval for the true proportion of women shoppers who shop on impulse? 0.148

Question 16 4 points Save A random sample of 70 voters found that 40% were going to vote for a certain candidate. Find the 95% limit for the population proportion of voters who will vote for that candidate. 28.5% < p < 51.5%

29.4% < p < 50.6% 30.4% < p < 49.6% 34.3% < p < 45.7%

Question 17 4 points Save A random sample of 95 printers discovered that 15 of them were being used in small businesses . Find the 99% limit for the population proportion of printers that are used in small businesses. -0.026 < p < 0.341 0.062 < p < 0.254 0.071 < p < 0.245 0.126 < p < 0.190

Question 18 4 points Save In a sample of 60 mice, a biologist found that 42% were able to run a maze in 30 seconds or less. Find the 95% limit for the population proportion of mice who can run that maze in 30 seconds or less. 35.8% < p < 48.2% 31.5% < p < 52.5% 29.5% < p < 54.5% 23.3% < p < 60.7%

Question 19 4 points Save In a sample of 855 bartenders, 48% heard complaints from patrons about work. If the margin of error was 4.4%, what was the confidence level that was used? 90%

95% 98% 99%

Question 20 4 points Save A recent poll of 700 people who work indoors found that 278 of them smoke. If the researchers want to be 98% confident of their results to within 3.5%, how large a sample is necessary? 751

1062 1301 532

Question 21 4 points Save The Academy of Orthopedic Surgeons states that 80% of women wear shoes that are too small for their feet. A researcher wants to be 98% confident that this proportion is within 3% of the true proportion. How large a sample is necessary? 966 683 1183 484

Question 22 4 points Save A report states that 40% of home owners had a vegetable garden. How large a sample is needed to estimate the true proportion of home owners who have vegetable gardens to within 6% with 95% confidence? 65 129 257 514

Question 23 4 points Save A report states that 42% of home owners had a vegetable garden. How large a sample is needed to estimate the true proportion of home owners who have vegetable gardens to within 5% with 96% confidence? 121 206 242 411

Question 24 4 points Save A sample of 1,108 was used to estimate a proportion with 98% confidence. If , what was the amount of error? 0.040 0.025 0.035 0.028

Question 25 4 points Save John Davis, a manager of a supermarket, wants to estimate the proportion of customers that will be using food stamps at his store. How large a sample is required to estimate the true proportion to within 3% with 98% confidence? 756 1,849 1,067 1,509

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