Question 5A sample size of 36 provides a sample mean of 10. If the population variance is known to be 16 and the population distribution is assumed to be normal, what is the lower limit for a 99% confidence interval?11.71738.85518.28273.130

7Question 6From a sample of 14 motorists working in Cape Town, the sample average time that it takes them to drive to work is 36 minutes with a standard deviation of 20 minutes. Construct a 99% confidence interval for the actual average time it takes all motorists in Cape Town to drive to work. What is the lower limit of the interval?

Question 7The county clerk wants to estimate the proportion of voters who willneed special election facilities. Suppose a sample of 400 voters was

taken. If 150 need special election facilities, calculate a 90% confidence interval for the population proportion. What is the upper limit of the confidence interval?

Question 8The national electricity supplier claims that switching off the hot water cylinder at night does not result in saving of electricity. In order to test this claim a newspaper reporter obtains the co-operation of 20 house owners with similar houses and salaries. Ten of the selected owners switch their cylinders off at night. The consumption of electricity in each house over a period of 30 days is measured; the units are kWh (kilowatt-hours). For households that switched off their hot water cylinders (group 1), average consumption over the 30 days was 690kWh with a variance of 460kWh2. For those that did not switch off their hot water cylinders, average electricity consumption was 720kWh with a variance of 360kWh2. Test at 10% significance level the assumption that the average consumption is lower if the cylinder is switched off. What is your decision?

Question 9A statistic is a number that describes a sample characteristic.TrueFalse

Question 10A powerful women's group has claimed that men and women differ in attitudes about sexual discrimination. A group of 50 men (group 1) and 40 women (group 2) were asked if they thought sexual discrimination is a problem in South Africa. Of those sampled, 11 of the men and 19 of the women did believe that sexual discrimination is a problem. Construct a 90% confidence interval for the difference between the population proportions . What is the lower limit?

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