1 of5

A random sample of 30 households was selected as part of a study on energy usage in a small community, and the number of kilowatt-hours (kWh) was recorded for each household in the sample for the March quarter of 2020. The data were approximately normally distributed with a mean of 375 kWh and a sample standard deviation of 85. A researcher intends to determine a 99% confidence interval for the population mean electricity usage during the period. Respond to the prompts that follow. (1 point each)

1. Will this confidence interval calculation be based on a z-interval or a t-interval? What is the rationale for that?
2. What is the point estimate for the confidence interval and how did you determine this?
3. What is the critical value of z or t to be used and the df, if required?
4. Describe how to calculate the standard error SE and show the calculations using the data for this scenario.
5. Assuming that usage is normally distributed, calculate a 99% confidence interval for the community's mean electricity usage in the March quarter of 2020.

Question

2 of5

During the pandemic, online ordering of groceries and household supplies was offered by many stores as an accommodation for shoppers who preferred not to visit crowded stores in person. An online grocery shopping service claims that its mean delivery time is less than 120 minutes with a population standard deviation of 30 minutes. A random sample of 49 orders is delivered with a mean of 100 minutes. At the 95% confidence level, is there enough evidence to support the claim? Assume the data are normally distributed. Use the critical value method and respond to the prompts below. (1 point each)

1. State the null and alternative hypotheses in words and in symbols.
2. What statistical test would be appropriate in this case and would it be right-tailed, left-tailed or two-tailed? Give the rationale for your choice.
3. Identify the critical value for the test.
4. Calculate the value of the test statistic. Please show the calculations also.
5. State a decision based on the calculated value of the test statistic and provide a rationale for that decision.

Question

3 of5

A hospital administrator has set a goal of having arriving patients seen in the same amount of time whether they arrive at the hospital's Emergency Room or the Urgent Care clinic. The hospital clinical services director thinks they are not meeting the goal of equal "time to be seen" yet and has collected data from arriving patients to use in a statistical test.

The director has decided to use an alpha of .05 and the p-value approach in her statistical test. She has determined that the data are normally distributed. Respond to the prompts that follow. (1 point each)

1. State the null and alternative hypotheses in words and in symbols.
2. What statistical test would be appropriate in this case and would it be right-tailed, left-tailed or two-tailed? Give the rationale for your choice.
3. Calculate the standard error of the test statistic.
4. Calculate the value of the test statistic and report the p-value (use technology for the p-value).
5. State a decision based on the calculated value of the test statistic and its p-value and provide a rationale for that decision.

4 of5 The contingency table below shows some categories of data along with frequency counts. Respond to the prompts that follow. (1 point each) Flavor Number of Pieces Expected Number of (10 bags) Pieces Apple Lime Cherry Mango Grape a. What statistical test would most likely be used with this data? What is the rationale for your choice? b. State the null and alternative hypotheses for the appropriate test. 0. What is the critical value ofthe test statistic? Use a = .05 d. What is the calculated value of the test statistic? e. State the conclusion for this statistical test