# MCQs: Confidence Intervals

1. A sample of n=9 college students is used to evaluate the effectiveness of a new Study Skills Workshop. Each student's grade point average (GPA) is recorded for the semester before the workshop and for the semester after the workshop. The average GPA improved by MD = 0.60 points with s2 = 0.09. The researcher would like to use the sample to estimate how much effect the workshop would have for the entire college population. Which of the following is the 80% confidence interval for these data?

Choose the correct answer and explain why

a) ? D = 0.60 Â± 0.01(1.397)

b) ? D = 0.60 Â± 0.09(1.860)

c) ? D = 0.60 Â± 0.10(1.397)

d) ? D = 0.60 Â± 0.10(1.860)

2. The larger the differences among the sample means, the larger the numerator of the F-ratio will be.

Please choose the answer:

a) True

b)False

3. A sample of n = 5 scores has a mean of M = 45 and a variance of s2 = 20. Using this sample, the 90% confidence interval for the population mean is

Please choose the correct answer:

a) ?= 45 Â± 2.776(?20)

b) ? = 45 Â± 2.776(2)

c) ? = 45 Â± 2.132(?20)

d) ? = 45 Â± 2.132(2)

4. For confidence intervals, precision increases as the interval gets wider.

Please choose the correct answer:

a) True

b) False

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1. A sample of n=9 college students is used to evaluate the effectiveness of a new Study Skills Workshop. Each student's grade point average (GPA) is recorded for the semester before the workshop and for the semester after the workshop. The average GPA improved by MD = 0.60 points with s2 = 0.09. The researcher would like to use the sample to estimate ...

#### Solution Summary

The solution provides answers to multiple choice questions on confidence interval. Formula for the calculation and Interpretations of the results are also included.