The waiting time to check out of a supermarket has had a population mean of 11.02 minutes.Recently,in an effort to reduce the waiting time,the supermarket has experimented with a system in which there is a single waiting line with multiple checkout servers.A sample of 50 customers was selected,and their mean waiting time to check out was 9.79 minutes with a sample standard deviation of 5.6 minutes.Complete parts(a)through(d). Click here to view page 1 of the critical values for the t distribution. Click here to view page 2 of the critical values for the t Distribution. a.At the 0.01 level of significance,using the critical value approach to hypothesis testing,is there evidence that the population mean waiting time to check out is less than 11.02 minutes? What are the null and alternative hypotheses for this test?

The waiting time to check out of a supermarket has had a population mean of 8.49 minutes.Recently,in an effort to reduce the waiting time,the supermarket has experimented with a system in deviation of 4.9 minutes.Complete parts(a)through(d). Click here to view page 1 of the critical values for the t Distribution Click here to view page 2 of the critical values for the t Distribution. a.At the 0.01 level of significance,using the critical value approach to hypothesis testing,is there evidence that the population mean waiting time to check out is less than 8.49 minutes?H0:μ≥8.49 H1:μ<8.49 What is the test statistic for this​ test?

The waiting time to check out of a supermarket has had a population mean of 8.49 minutes.Recently,in an effort to reduce the waiting time,the supermarket has experimented with a system in which there is a single waiting line with multiple checkout servers.A sample of 90 customers was selected,and their mean waiting time to check out was 7.85 minutes with a sample standard deviation of 4.9 minutes.Complete parts(a)through(d) H0:μ≥8.49 H1:μ<8.49 What is the test statistic for this test? -1.2391 (Round to four decimal places as needed.) What is the critical value for this test?

The manager of a grocery store has taken a random sample of 100 customers to determine whether or not the mean waiting time of all customers is significantly more than 3 minutes. She observes that the average length of time it took the customers in the sample to check out was 3.1 minutes. The population standard deviation is known to be 0.5 minutes.

Customers waiting at Ellerton Bank have been complaining about the amount of time they must wait in line. Managers at the bank, beginning to investigate the problem, have recorded sample waiting times for 19 customers at the bank. Here are the 19 waiting times (in minutes).2, 3, 4, 5, 5, 5, 6, 6, 9, 10, 11, 12, 15, 15, 20, 21, 28, 31, 37Send data to calculator86420Frequency862210816243240waiting time (in minutes)(a) Which measures of central tendency do not exist for this data set? Choose all that apply.MeanMedianModeNone of these measures(b) Suppose that the measurement 37 (the largest measurement in the data set) were replaced by 59. Which measures of central tendency would be affected by the change? Choose all that apply.MeanMedianModeNone of these measures(c) Suppose that, starting with the original data set, the largest measurement were removed. Which measures of central tendency would be changed from those of the original data set? Choose all that apply.MeanMedianModeNone of these measures(d) Which of the following best describes the distribution of the original data? Choose only one.

The post office, which has separate lines at different windows, determines that the standard deviation for customer waiting times on Friday afternoons is 7.2 minutes. The post office decides to experiment with a single, main waiting line. For a random sample of 25 customers, it is found that the waiting times have a standard deviation of 3.5 minutes on a Friday afternoon. At a 5% significance level, the post office wants to test the assertion that a single line results in less variation in waiting times for customers. Give your conclusion.