South.mpls.k12.mn.us



Try to find an exam question to replace #12Ch. 8 ReviewA commercial for a breakfast cereal is shown during a certain television program. The manufacturer of the cereal wants to estimate the percent of television viewers who watch the program. The manufacturer wants the estimate to have a margin of error of at most 0.02 at a level of 95 percent confidence. Of the following, which is the smallest sample size that will satisfy the manufacturer’s requirements?40501001,7002,500A statistician proposed a new method for constructing a 90 percent confidence interval to estimate the median of assessed home values for homes in a large community. To test the method, the statistician will conduct a simulation by selecting 10,000 random samples of the same size from the population. For each sample, a confidence interval will be constructed using the new method. If the confidence level associated with the new method is actually 90 percent, which of the following will be captured by approximately 9,000 of the confidence intervals constructed from the simulation?The sample meanThe sample medianThe sample standard deviationThe population meanThe population medianA botanist collected one leaf at random from each of 10 randomly selected mature maple trees of the same species. The mean and the standard deviation of the surface areas for the 10 leaves in the sample were computed. Assume the distribution of surface areas of maple leaves is normal. What is the appropriate method for constructing a one-sample confidence interval to estimate the population mean surface area of the species of maple leaves, and why is the method appropriate?The t-interval is appropriate, because the population standard deviation is not known.The t-interval is appropriate, because the t-interval is narrower than the z-interval.The z-interval is appropriate, because the z-interval is narrower than the t-interval.The z-interval is appropriate, because the central limit theorem applies.The z-interval is appropriate, because the sample standard deviation is known.A school administrator is interested in estimating the proportion of students in the district who participate in community service activities. From a random sample of 100 students in the district, the administrtor will construct a 99 percent confidence interval for the proportion of all district students who participate in community service activities. Which of the following statements must be true?The population proportion will be in the confidence interval.The probability that the confidence interval will include the population proportion is 0.99.The probability that the confidence interval will include the sample proportion is 0.99.The population proportion and the sample proportion will be equal.The probability that the population proportion and the sample proportion will be equal is 0.99.Based on previous research, the standard deviation of the distribution of the age at which children begin to walk is estimated to be 1.5 months. A random sample of children will be selected, and the age at which each child begins to walk will be recorded. A 99 percent confidence interval for the average age at which children begin to walk will be constructed using the data obtained from the sample of children. Of the following, which is the smallest sample size that will result in a margin of error of 0.1 month or less for the confidence interval?4009001,3001,6002,100A random sample of 432 voters revealed that 100 are in favor of a certain bond issue. A 95 percent confidence interval for the proportion of the population of voters who are in favor of the bond issue is100 ±1.960.5(0.5)432100 ±1.6450.5(0.5)432100 ±1.960.231(0.769)4320.231 ±1.960.231(0.769)4320.231 ±1.6450.231(0.769)432Based on a survey of a random sample of 900 adults in the United States, a journalist reports that 60 percent of adults in the United States are in favor of increasing the minimum hourly wage. If the reported percent has a margin of error of 2.7 percentage points, which of the following is closest to the level of confidence?80.0%90.0%95.0%95.5%99.0%When using a one-sample t-procedure to construct a confidence interval for the mean of a finite population, a condition is that the population size be at least 10 times the sample size. The reason for the condition is to ensure thatthe sample size is large enoughthe central limit theorem is applicable for the sample meanthe sample standard deviation is a good approximation of the population standard deviationthe degree of dependence among observations is negligiblethe sampling method is not biasedA news article reported that college students who have part-time jobs work an average of 15 hours per week. The staff of a college newspaper thought that the average might be different from 15 hours per week for their college. Data were collected on the number of hours worked per week for a random sample of students at the college who have part-time jobs. The results of the sample are shown below.Sample MeanStd Errordft-statistic13.7550.70725-1.761Which of the following represents a 95% confidence interval for μ?13.755±0.24413.755±0.28613.755±0.70713.755±1.24513.755±1.456A polling agency conducted a survey by selecting 100 random samples, each consisting of 1,200 United States citizens. The citizens in each sample were asked whether they were optimistic about the economy. For each sample, the polling agency created a 95 percent confidence interval for the proportion of all United States citizens who were optimistic about the economy. Which of the following statements is the best interpretation of the 95 percent confidence level?With 100 confidence intervals, we can be 95% confident that the sample proportion of citizens of the United States who are optimistic about the economy is correct.We would expect about 95 of the 100 confidence intervals to contain the proportion of all citizens of the United States who are optimistic about the economy.We would expect about 5 of the 100 confidence intervals to not contain the sample proportion of citizens of the United States who are optimistic about the economy.Of the 100 confidence intervals, 95 of the intervals will be identical because they were constructed from samples of the same size of 1,200.The probability is 0.95 that 100 confidence intervals will yield the same information about the sample proportion of citizens of the United States who are optimistic about the economy.Some boxes of a certain brand of breakfast cereal include a voucher for a free DVD rental inside the box. The company that makes the cereal claims that a voucher can be found in 20 percent of the boxes. However, based on their experiences eating this cereal at home, a group of students believes that the proportion of boxes with vouchers is less than 0.2. This group of students purchased 65 boxes of the cereal to investigate the company’s claim. The students found a total of 11 vouchers for free video rentals in the 65 boxes.Suppose it is reasonable to assume that the 65 boxes purchased by the students are a random sample of all boxes in this cereal. Construct a 95% confidence interval to estimate the proportion of boxes with vouchers.Based on this interval, is there support for the students’ belief that the proportion of boxes with vouchers is not 0.2? Provide statistical evidence to support your answer. A simple random sample of 101 students at South High School is taken. The mean grade point average of these students (on a 4-point scale) was 3.12 with a standard deviation of .35. Construct a 95% confidence interval for the mean grade point average of all South students. (Follow the 4-step Process) ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download