In the past, patrons of a cinema complex have spent an average of $2.50 for popcorn and snacks. The amounts of these expenditures have been normally distributed. Following an intensive publicity campaign by a local medical society, the mean expenditure for a sample patrons is found to be $2.10. The standard deviation is found to be $0.90. Which of the following represents a 99% confidence interval for the population average amount spent E patrons of a cinema complex on popcorn and other snacks following an intensive publicity campaign by a local medical society? O ($1.73, $2.47) O ($1.65, $2.55) O($1.82, $2.38) O ($1.49, $2.71) O ($1.56, $2.64) ♫ MA W

In a random sample of 5 mobile​ devices, the mean repair cost was ​$60.00 and the standard deviation was ​$12.00. Assume the population is normally distributed and use a​ t-distribution to find the margin of error and construct a 95​% confidence interval for the population mean. Interpret the results.

The average gold content from an ore sample in 36 different locations is found to be 2.6 grams per ton. a. Find the 95% and 99% confidence intervals for the mean gold content in that area. Assume that the population variance is 0.09.

Exercise 3. A personal manager has found that historically the scores on aptitude tests given to applicants for entry-level positions follow a normal distribution with a standard deviation of 32.4 points. A random sample of nine test scores from the current group of applicants had a mean score of 187.9 points. a. Find an 80% confidence interval for the population mean score of the current group of applicants. b. Based on these sample results a statistician found for the population mean a confidence interval extending from 165.8 to 210.0 points. Find the confidence level of this interval.

In a sample of seven cars, each car was tested for nitrogen oxide emissions (in grams per mile). The results appear below. Assuming that nitrogen oxide emissions are normally distributed, 4. Car 1 2 3 4 5 6 7 Nitrogen oxide emission (g/mi) 0.13 0.18 0.15 0.09 0.12 0.18 0.08 a. Construct a 95% confidence interval for the mean amount of nitrogen oxide emissions for all cars. b. What effect would increasing the level of confidence have on the length of the interval?

A study was conducted to estimate hospital costs for car accident victims who woreseat belts. Suppose that 46 randomly selected cases had an average of $15150and a standard deviation of $8500. If the average hospital costs for those that didnot wear seatbelts was $19000, construct a 90% confidence interval to see if theaverage costs are significantly different.

In a random sample of ten cell​ phones, the mean full retail price was ​$433.00 and the standard deviation was ​$208.00. Assume the population is normally distributed and use the​ t-distribution to find the margin of error and construct a 99​% confidence interval for the population mean μ. Interpret the results.

In September a biological research team caught, weighed, and released a random sample of 24 chipmunks in Rocky Mountain National Park. The mean of the sample weights was x-bar = 8.7 oz. with sample standard deviation s = 1.4 oz. Find a 90% confidence interval for the mean September weight of all chipmunks in Rocky Mountain National Park.

A technician compares repair costs for two types of microwave ovens (type I and type II). He believes that the repair cost for type I ovens is greater than the repair cost for type II ovens. A sample of 35 type I ovens has a mean repair cost of $80.39. The population standard deviation for the repair of type I ovens is known to be $24.63. A sample of 31 type II ovens has a mean repair cost of $73.47. The population standard deviation for the repair of type II ovens is known to be $10.42. Conduct a hypothesis test of the technician's claim at the 0.05 level of significance. Let i be the true mean repair cost for type I ovens and µz be the true mean repair cost for type II ovens. Step 1 of 5: State the null and alternative hypotheses for the test.