Lab 5
De Sousa, Daniel Mr ()
Started: March 11, 2008 9:32 PM
Questions: 16
Instructions
All questions of this lab 5 are based on material from chapter 11.(*)
It is available till Wednesday, March 12, 2008, 10:00am. Each student has to submit her/his own lab (no group work). You have the choice of 3 attempts; each attempt has a duration of 5 hours. The latest submission will be counted for your marks. If the time for the actual attempt has expired, you have to finish this attempt by clicking the button ‘Finish’ at the top of the page, in order to access a new attempt. Don't forget to save your answers before submitting the lab.
(*) Some questions/data rely on Levine, Krehbiel, Berenson: Business Statistics: a first course (3rd edition, 2003)
1. L5Q1
(Points: 1)
Which of the following would be an appropriate null hypothesis?
a. The mean of a population is equal to 55.
b. The mean of a sample is equal to 55.
c. The mean of a population is greater than 55.
d. Only (a) and (c) are true.
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2. L5Q2
(Points: 1)
A Type I error is committed when
a. we reject a null hypothesis that is true.
b. we don’t reject a null hypothesis that is true.
c. we don’t reject a null hypothesis that is false.
d. we reject a null hypothesis that is false.
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3. L5Q3
(Points: 1)
True or false: For a given sample size, the probability of committing a Type II error will increase when the probability of committing a Type I error is reduced.
TrueFalse
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4. L5Q4
(Points: 1)
If an economist wishes to determine whether there is evidence that average family income in a community exceeds $25,000
a. either a one-tailed or two-tailed test could be used with equivalent results.
b. a one-tailed test should be utilized.
c. a two-tailed test should be utilized.
d. None of the above.
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5. L5Q5
(Points: 1)
If the p-value is less than a,
a. the alternative hypothesis should be rejected.
b. no conclusion should be reached.
c. the null hypothesis should not be rejected.
d. the null hypothesis should be rejected.
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6. L5Q6
(Points: 1)
Researchers determined that about 60 tissues are used during a cold. Suppose a random sample of 100 Kleenex users yielded the following data on the number of tissues used during a cold: equation= 52, s = 22. Give the null and alternative hypotheses to test a claim that the number of tissues used during a cold is less than 60.
a. H0: equation= 52 and H1: equation≠ 52.
b. H0: equation≥ 60 and H1: equation< 60.
c. H0: m ≤ 60 and H1: m > 60.
d. H0: m ≥ 60 and H1: m < 60.
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7. L5Q7
(Points: 1)
A ___ is a numerical quantity computed from the data of a sample and is used in reaching a decision on whether or not to reject the null hypothesis.
a. significance level
b. parameter
c. test statistic
d. critical value
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8. L5Q8
(Points: 1)
A manager of the credit department for an oil company would like to determine whether the average monthly balance of credit card holders is equal to $75. An auditor selects a random sample of 100 accounts and finds that the average owed is $83.40 with a sample standard deviation of $23.65. If you wanted to test whether the auditor should conclude that there is evidence that the average balance is different form $75, which test would you use?
a. z-Test for the population mean
b. t-Test for the population mean
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9. L5Q9
(Points: 1)
A manager of the credit department for an oil company is examining the average monthly balance of credit card holders. An auditor selects a random sample of 100 accounts and finds that the average balance owed is $83.40 with a sample standard deviation of $23.65. If you wanted to test whether the average balance owed is different from $75 and decided to reject the null hypothesis, what conclusion could you draw?
a. There is not enough evidence to claim that the average balance is $75.
b. There is sufficient evidence to claim that the average balance is not $75.
c. There is sufficient evidence to claim that the average balance is $75.
d. There is not enough evidence to claim that the average balance is not $75.
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10. L5Q10
(Points: 1)
True or false: When calculating the appropriate sample size required to obtain a given level of precision, a fractional result should always be rounded up to the nearest integer.
TrueFalse
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11. L5Q11
(Points: 1)
In a two-tailed test of the mean where a = 0.05 and the population standard deviation in known, what is/are the critical value(s)?
a. ±1.96
b. 1.645
c. ±1.645
d. 1.96
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12. L5Q12
(Points: 1)
You have just conducted a hypothesis test in which you found a p-value of 0.03 and you rejected H0. Which statement about the level of significance, a, must be true?
a. a ≤ 0.03
b. a = 0.03
c. a ≥ 0.03
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13. L5Q13
(Points: 1)
Given a two-tailed test for the population mean, the null hypothesis always contains a(n) ___ sign, and the alternative hypothesis always contains a(n) ___ sign.
a. ≥, <
b. =, ≠
c. ≠, =
d. ≤, >
e. <, ≥
f. >, ≤
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14. L5Q14
(Points: 1)
The value that separates a rejection region from a non-rejection region is called the ____Fill in the Blank 01.
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15. L5Q15
(Points: 5)
Suppose the proportion of statistics students that are female is believed to be 0.54. What sample size would be necessary if we wanted to estimate the true proportion to within ±8% using a 95% level of confidence? (For full marks show your calculation and write an answer statement with the correct result.)
Paragraph
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16. L5Q16
(Points: 21)
An angry consumer claims that a cola manufacturer fills bottles labelled ‘2 litres’ with less than 2 litres of cola, on average. Test that claim using the 0.04 level of significance. Base the test on a random sample of 20 bottles of their cola. For the sample, the mean amount of cola in a bottle is 1.96 litres, and the standard deviation is 0.11 litres. The distribution of cola amounts in the bottles is approximately normal.
a) (2 marks) Show step 1.
b) (4 marks) Show step 2.
c) (1 mark) Show step 3.
d) (3 marks) Show step 4.
e) (1 mark) This is a ___-tailed test.
f) (2 marks) Determine the critical value(s). (It is optional to show work. Show final result with 4 decimal places.)
g) (6 marks) Show step 6/7. (For full marks show your calculation. Show final result with 3 decimal places.)
h) (2 marks) Show step 8.
Paragrapha) Step 1 b) Step 2 c) Step 3 d) Step 4 e) This is a ___-tailed test. f) Critical value(s) g) Step 6/7 h) Step 8
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