A 271 b 385 c 543 d 646 e 1234 g a study reports a

Info icon This preview shows pages 5–7. Sign up to view the full content.

View Full Document Right Arrow Icon
__ A. 271 __ B. 385 __ C. 543 __ D. 646 __ E. 1234 g) A study reports a correlation of r = -0.71 between family income in dollars and the number of pounds of soft margarine the family consumes in a year. You conclude that: __ A. This is nonsense – you can’t compute a correlation between income and amount of margarine __ B. Something is wrong – a correlation can’t take the value -0.71. __ C. Higher income families consume less soft margarine than do lower income families __ D. Higher income families consume more soft margarine than do lower income families h) Which of the following is an incorrect statement about the correlation between two quantitative variables X and Y ? __ A. A correlation of -0.8 indicates a stronger linear association between X and Y than a correlation of 0.5. __ B. A correlation of 0 implies X and Y are not related at all. __ C. A correlation of -1 indicates that Y = - X . __ D. Both (B) and (C). __ E. Both (A) and (B). i) Previous surveys reported that more men than women trade stocks online. A local brokerage firm randomly selected a sample of investors and found that 45 out of 234 men traded online while 42 out of 251 women traded online. The 95% confidence interval for the difference in proportions is (-4% to 9%). From this we can conclude: __ A. ...that a significant difference exists in the proportions of men and women who trade stocks online. __ B. ...that more men than women trade stocks online. __ C. ...that more women than men trade stocks online. __ D. ...that there is no significant difference in the proportions of men and women who trade stocks online. __ E. Nothing, because we can't draw conclusions from confidence intervals. j) In a hypothesis test, the P-value of the test statistic is 0.063. This means that the test is statistically significant at: __A. ...both the 0.05 and 0.01 levels __B. ...the 0.05 level but not at the 0.01 level __C. ...the 0.01 level but not at the 0.05 level __D. ...neither the 0.05 nor the 0.01 levels __E. Can’t tell; the answer depends on the specific null and alternative hypotheses 5
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Question 2. (Total 8 marks) “Abnormally good questions about the normal” NOTE: This question has three unrelated parts. a) A manufacturer produces light bulbs with normally distributed length of life having mean of 500 hours and standard deviation of 20 hours. For how many hours should he guarantee his bulbs if he wishes no more than 2% to fail prior to guaranteed life length. SHOW YOUR WORK TO GET FULL MARKS. __ A. 459 __ B. 480 __ C. 500 __ D. 541 __ E. 560 b) Final exam grades in a large undergraduate class are normally distributed. Bill’s grade was 90% and his corresponding z-score was 2. Steve’s grade was 60% and his corresponding z-score was -1. What are the mean and standard deviation of the exam grades for the whole class? Report your answers to the nearest whole numbers. SHOW YOUR WORK TO GET FULL MARKS. Mean = __________ SD = _________ c) Chocolate bars produced by a certain machine are labeled as weighing 232 g. The distribution of the actual weights of these chocolate bars is claimed to be normal with a mean of 250 g. and a standard deviation of 24 g. If the quality control manager takes a random sample of 16 chocolate bars from the production line, what is the probability that the sample mean weight of the 16 bars will be less than 232 g.
Image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern