Lesson 4B.7.1
4B.7.1 One-sample t-test: Pearson Edexcel Further Maths, Unit 24
20 questions
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Lesson 4B.7.1, One-sample t-test: 20 multiple choice questions for the Pearson Edexcel Further Maths (9FM0), Unit 24: t-tests, written with Revision Ninja.
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The 20 questions
-
What is the test statistic for H0: mu = mu0 for a one-sample t-test with unknown sigma?
- (x-bar - mu0) / s
- (x-bar - mu0) / (s sqrt(n))
- (x-bar - mu0) / (s / sqrt(n))
- (x-bar - mu0) / (sigma / sqrt(n))
-
Which assumption is needed for the one-sample t-test to be valid for small samples?
- The population is discrete
- The population variance is known
- The sample must be paired
- The population is approximately normal
-
Why does the t distribution have heavier tails than the standard normal for small samples?
- The t distribution is used only for paired data
- The t distribution is always twice as wide as the standard normal
- Estimating sigma by s adds extra uncertainty, so the distribution is more spread out when the degrees of freedom are few
- The t distribution has a larger mean than the normal
-
What is a 95% confidence interval for mu when sigma is unknown?
- x-bar +/- t(n-1) sigma / sqrt(n)
- x-bar +/- t(n) s / n
- x-bar +/- s / sqrt(n-1)
- x-bar +/- t(n-1) s / sqrt(n), with the 95% t critical value
-
What is the two-tailed 5% critical t value with 15 degrees of freedom?
- 1.753
- 2.947
- 2.602
- 2.131
-
For H1: mu > mu0, which rejection region is used?
- Both tails equally, with half the significance level in each
- The lower tail only, where t is less than the negative critical value
- The upper tail, where t is greater than the positive critical value
- The central region between minus and plus the critical value
-
What is meant by the significance level of a hypothesis test?
- The proportion of the sample lying above the mean
- The probability that H0 is true
- The probability of rejecting H0 when H0 is actually true
- The sample size needed to achieve full power
-
A sample of n = 16 has mean 52 and s = 6. Test H0: mu = 50 against H1: mu not equal to 50. What is the test statistic?
- 1.50
- 1.33
- 0.33
- 3.00
-
For the statistic t = 1.33 with 15 df, what is the conclusion at the 5% two-tailed level? (Critical value 2.131.)
- Reject H0, since t is positive so the test is one-tailed
- Reject H0, since 1.33 exceeds 1.753
- Do not reject H0, since |t| = 1.33 is below 2.131
- The test cannot be carried out because the sample is too small for t
-
A sample of n = 25 has mean 10.4 and s = 2. Test H0: mu = 10. What is the test statistic?
- 2.0
- 1.0
- 0.2
- 5.0
-
Using the sample in the previous setting (n = 25, mean 10.4, s = 2), what is the 95% confidence interval for the mean, to 2 decimal places? (t value with 24 df is 2.064.)
- (8.40, 12.40)
- (9.57, 11.23)
- (9.97, 10.83)
- (9.62, 11.18)
-
A sample of n = 9 has mean 23 and s = 4. Test H0: mu = 20 against H1: mu > 20 at the 5% level. What is the test statistic?
- 0.75
- 6.00
- 2.25
- 1.33
-
A sample of n = 10 has mean 5 and s = 2. What is the half-width of the 95% confidence interval for the mean, to 2 decimal places? (t value with 9 df is 2.262.)
- 1.43
- 0.63
- 1.96
- 2.26
-
A small sample comes from a strongly skewed population. How reliable is the one-sample t-test?
- Less reliable, so normality should be checked or a non-parametric alternative considered
- Valid only if the population variance is known
- Perfectly valid regardless of the population shape
- Always valid whenever n is at least 2
-
A sample of n = 36 has mean 47 and s = 6. Test H0: mu = 50 against H1: mu not equal to 50. What is the test statistic?
- -3.00
- -6.00
- 3.00
- -0.50
-
For a test statistic t = 2.5 with 20 df, what is the two-tailed p-value, to 2 decimal places?
- 0.02
- 0.01
- 0.10
- 0.05
-
A sample of n = 17 has mean 50 and s = 8. What is the 95% confidence interval for the mean, to 2 decimal places? (t value with 16 df is 2.120.)
- (46.00, 54.00)
- (48.04, 51.96)
- (45.89, 54.11)
- (42.00, 58.00)
-
A sample of n = 10 has mean 62 and s = 8. Test H0: mu = 60 against H1: mu not equal to 60 at the 5% level. What is the conclusion? (Critical value 2.262 with 9 df.)
- Cannot be concluded, since the population standard deviation is unknown
- Significant at 5%, since t is about 2.53
- Significant, since 62 is greater than 60
- Not significant, since t of about 0.79 is below 2.262
-
Why do the degrees of freedom matter for the t critical value?
- Fewer degrees of freedom make s a less precise estimate of sigma, so the critical value is larger
- Degrees of freedom equal n, so no adjustment to the critical value is needed
- Larger degrees of freedom give heavier tails, so the critical value is larger
- Degrees of freedom count the parameters, so t is always symmetric about the mean
-
A test gives a two-tailed p-value of 0.04 and a student concludes that the population mean differs from mu0 with 99% certainty. Which evaluation is correct?
- Incorrect, because a two-tailed p-value is always smaller than a one-tailed p-value
- Incorrect: the p-value is not the probability that H0 is true, and significance at 5% does not imply 99% certainty
- Correct: a p-value of 0.04 means there is a 4% chance that mu equals mu0 exactly
- Correct: a p-value below 0.05 implies 99% certainty of the conclusion
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