COMM 207 - Assignment I
Due date: Friday January 24th11:59 PM via Crowdmark
Please use Word. To see an example of using the equation editor in Word, please see the video “How to use Word for Equations” posted under Course Materials.
You may use Excel for your calculations if you wish, but you need to show your work for calculating test statistics on this assignment. Show: i) the equation you chose ii) how you plug in values, and iii) your final rounded answer. See below for details on rounding.
Save your answer to each question as a PDF document. Upload your saved PDF document to the appropriate location in Crowdmark. You will receive an email from Crowdmark with your individual submission instructions by Tuesday January 14that the latest. Do not delete this email.Take a screenshot of the “Thank you for your submission” message on Crowdmark after you submit; this is your proof of submission.
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Use your USask email address and BlackBoard password. If it doesn't work right away, please click the "Forgot my password" link, and a reset email will be sent to your USask email address.
Remember: You need to use theexactemail address that the Crowdmark email was sent to. That might mean you need to use "@mail.usask.ca", not "@usask.ca" in your email address. You need to check which email address received the Crowdmark email. If the steps above did not work for you, please send me an email with a screenshot of the error message you receiveat least 24 hours priorto the due date.
For questions that ask you to conduct an appropriate hypothesis test, please show all of the following:
1)A statement of the null and alternative hypotheses in words or symbols
2)The calculation of an appropriate test statistic (show your work: show which equation you chose, the values you plug in, and your final rounded answer)
For test statistics involving the t-distribution: round to 3 decimal places.
For test statistics involving the Normal distribution: round to 2 decimal places.
3)Calculation of the p-value or critical value, as appropriate (show your work: write the appropriate probability statement and how you manipulate it as necessary – e.g. using the one-minus trick – and state your final probability)
4)Conclusion: do you reject the null hypothesis? Why or why not?
5)Interpretation:onesentence explaining what the conclusion means in the context of the original research question.
For other questions, please answer inone sentence.
1.A video game company is interested in knowing the population mean number of hours spent playing a new game from start to finish. If the game takes longer than 50 hours to play, on average, then it will need to be re-worked. The company collects a sample of 49 video game players with various levels of expertise, and finds that it takes them 48 hours, on average, to complete the game, with a standard deviation of 1.5 hours.
a.Conduct an appropriate hypothesis test using the critical value method. [7 marks]
b.Explain what a Type II Error means in this context. [1 mark]
2.A major furniture company has a line of couches designed for apartment dwellers. These couches need to be light enough to be carried up flights of stairs. The lead engineer wants to use a new type of material. The engineer claims that the new couches will be lighter than the old couches.
They take a sample of 10 couches manufactured using the old material and compute an average weight of 350 lbs with a standard deviation of 20 lbs.
They take a sample of 10 couches manufactured using the new material and compute an average weight of 340 lbs with a standard deviation of 15 lbs.
a.Conduct an appropriate hypothesis test using the p-value method. Use the old material as population 1. [8 marks]
b.How much evidence is there against the null hypothesis in part (a)? [1 mark]
c.Explain what a Type I Error means in this context. [1 mark]
3.A chocolate company markets a 500g box of chocolates to large retail stores for Valentine’s Day. This year, they project the mean order quantity will be greater than last year. Last year, the mean order quantity was 500 boxes per large retail store. This year, a random sample of 4 large retail stores gave a sample mean order quantity of 490 boxes. Assume a population standard deviation of 50 boxes, and that the mean order quantity follows a Normal distribution.
Conduct a hypothesis testusing the critical value methodto determine whether this year’s population mean order quantity is more than 10% lower than last year’s.HINT: What is meant by “more than 10% lower”? For example, it might be 10.8885% lower, or 14.68% lower, etc. What does that mean in terms of “number of boxes”? You have to figure that out to answer this question. [7 marks]