PSY 230 Final Exam Study Guide
UPDATED Exam Questions and CORRECT
Answers
What is the critical Z value for an 80% confidence interval? - CORRECT ANSWER -1
What is the critical Z value for a 90% confidence interval? - CORRECT ANSWER -1
What is the critical Z value for a 95% confidence interval? - CORRECT ANSWER -1
What is the critical Z value for a 99% confidence interval? - CORRECT ANSWER -2
How does the confidence level affect the width of a confidence interval? - CORRECT
ANSWER -A higher confidence level results in a wider confidence interval.
Which factors impact the margin of error of a confidence interval about the mean? - CORRECT
ANSWER -Sample size, confidence level, standard deviation.
How do you compute the 90% confidence interval for the proportion of heads observed when
flipping a coin 100 times with 65 heads? - CORRECT ANSWER -The 90% confidence
interval is (0.65 - 0.086, 0.65 + 0.086) or (0.564, 0.736).
What is the 95% confidence interval for the proportion of people who enjoyed the new park if 60
out of 75 surveyed enjoyed it? - CORRECT ANSWER -The 95% confidence interval is
approximately (0.703, 0.797).
How do you compute the 95% confidence interval for the mean weight of cereal bags if the
sample mean is 77 ounces and the standard deviation is 7 ounces? - CORRECT
ANSWER -The 95% confidence interval is (75.56, 78.44) ounces.
, What is the 90% confidence interval for the mean recovery time if the mean is 46.3 days and the
population standard deviation is 12 days? - CORRECT ANSWER -The 90% confidence
interval is approximately (43.93, 48.67) days.
What is the minimum sample size required for a 95% confidence interval with a margin of error
of 5 and a population standard deviation of 10? - CORRECT ANSWER -The minimum
sample size required is 96.
What is the minimum sample size required for a 90% confidence interval with a margin of error
of 2 and a population standard deviation of 5? - CORRECT ANSWER -The minimum
sample size required is 69.
What is the minimum sample size required for a 99% confidence interval with a margin of error
of 10 and a population standard deviation of 25? - CORRECT ANSWER -The minimum
sample size required is 61.
What does a confidence interval tell us? - CORRECT ANSWER -It provides a range of
values within which we expect the true population parameter to lie.
What does a confidence interval not tell us? - CORRECT ANSWER -It does not provide
the exact value of the population parameter.
What conclusions can be made from a hypothesis test? - CORRECT ANSWER -We can
either reject or fail to reject the null hypothesis based on the evidence.
What is the left-tailed hypothesis for a mean? - CORRECT ANSWER -H0: μ ≥ μ0, Ha: μ
< μ0.
What is the right-tailed hypothesis for a mean? - CORRECT ANSWER -H0: μ ≤ μ0, Ha: μ
> μ0.
UPDATED Exam Questions and CORRECT
Answers
What is the critical Z value for an 80% confidence interval? - CORRECT ANSWER -1
What is the critical Z value for a 90% confidence interval? - CORRECT ANSWER -1
What is the critical Z value for a 95% confidence interval? - CORRECT ANSWER -1
What is the critical Z value for a 99% confidence interval? - CORRECT ANSWER -2
How does the confidence level affect the width of a confidence interval? - CORRECT
ANSWER -A higher confidence level results in a wider confidence interval.
Which factors impact the margin of error of a confidence interval about the mean? - CORRECT
ANSWER -Sample size, confidence level, standard deviation.
How do you compute the 90% confidence interval for the proportion of heads observed when
flipping a coin 100 times with 65 heads? - CORRECT ANSWER -The 90% confidence
interval is (0.65 - 0.086, 0.65 + 0.086) or (0.564, 0.736).
What is the 95% confidence interval for the proportion of people who enjoyed the new park if 60
out of 75 surveyed enjoyed it? - CORRECT ANSWER -The 95% confidence interval is
approximately (0.703, 0.797).
How do you compute the 95% confidence interval for the mean weight of cereal bags if the
sample mean is 77 ounces and the standard deviation is 7 ounces? - CORRECT
ANSWER -The 95% confidence interval is (75.56, 78.44) ounces.
, What is the 90% confidence interval for the mean recovery time if the mean is 46.3 days and the
population standard deviation is 12 days? - CORRECT ANSWER -The 90% confidence
interval is approximately (43.93, 48.67) days.
What is the minimum sample size required for a 95% confidence interval with a margin of error
of 5 and a population standard deviation of 10? - CORRECT ANSWER -The minimum
sample size required is 96.
What is the minimum sample size required for a 90% confidence interval with a margin of error
of 2 and a population standard deviation of 5? - CORRECT ANSWER -The minimum
sample size required is 69.
What is the minimum sample size required for a 99% confidence interval with a margin of error
of 10 and a population standard deviation of 25? - CORRECT ANSWER -The minimum
sample size required is 61.
What does a confidence interval tell us? - CORRECT ANSWER -It provides a range of
values within which we expect the true population parameter to lie.
What does a confidence interval not tell us? - CORRECT ANSWER -It does not provide
the exact value of the population parameter.
What conclusions can be made from a hypothesis test? - CORRECT ANSWER -We can
either reject or fail to reject the null hypothesis based on the evidence.
What is the left-tailed hypothesis for a mean? - CORRECT ANSWER -H0: μ ≥ μ0, Ha: μ
< μ0.
What is the right-tailed hypothesis for a mean? - CORRECT ANSWER -H0: μ ≤ μ0, Ha: μ
> μ0.
