Statistical Inference I — 2025 Past Questions

University of Ilorin STA121: 14 questions.

Topics: Test of hypothesis concerning population mean, Population and Sample, Random Sampling Distribution, Estimation

1. A matched pair experiment yielded the following differences: (4, -2, 3, 3, 3, -2, 0, 2, 0, 2) (4, 0, -1, 3, -1, 4, 3, 2, 3, 0) What is the value of the t-test statistic?
   1. -0.3946
   2. -0.4
   3. 0.3946
   4. 0.4
2. Accepting H¹ when H¹ is true is what?
   1. Correct decision
   2. Type I error
   3. Type II error
   4. Type III error
3. What is the power of a test?
   1. Type I error
   2. Type II error
   3. Type III error
   4. Rejecting H⁰ when H⁰ is false
4. X bar and S are examples of
   1. Statistics
   2. Estimators
   3. Parameters
   4. Estimate
5. ____ is a scientific figure usually 0.05, it is used to predict the p-value.
   1. Type I error
   2. Significance level
   3. Type II error
   4. Z-score
6. Rejecting H₀ when H₀ is false is
   1. Type I error
   2. Correct decision
   3. Type II error
   4. False hypothesis
7. Population is classified by these except
   1. Finite
   2. Non-finite
   3. Statistics
   4. Hypothetical
8. A survey of 60 students out of 100 students was made. To test p = 0.5, alpha = 0.05, what is the z-score?
   1. 1.96
   2. 1.64
   3. 2.0
   4. 3.5
9. A company claims its product lasts 10 hours. A sample of 16 products had a mean of 9.5 and a standard deviation of 1 hour. Calculate the t-statistic.
   1. -2
   2. -1.5
   3. 1.5
   4. 2
10. From a population of 1, 2, 3, 4, 5, a sample size of two was taken. How many sample distributions will be made with and without replacement?
    1. 25 with replacement, 10 without replacement
    2. 10 with replacement, 25 without replacement
    3. 5 with replacement, 5 without replacement
    4. 20 with replacement, 20 without replacement
11. Sample distribution of mean is
    1. Binomial
    2. Always normal
    3. Normal when the population is normal or the sample size is large
    4. Uniform
12. In a paired t-test, you can compare
    1. Two independent samples
    2. Population variance
    3. One sample of a population
    4. Two related groups
13. The probability of committing a Type I error is
    1. α (Alpha)
    2. β (Beta)
    3. 1 - β
    4. None of the above
14. A population can be represented as
    1. Statistics
    2. Parameter
    3. Inference
    4. Hypothesis

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