STA 2024 Exam 3 Study Guide with 100%
correct answers A+ rated
Which of the following is a correct interpretation of a p-value that is NOT very small> - correct answer
✔✔What we saw in the sample data is not surprising, so we fail to reject the null hypothesis.
An old myth claims that boys are better at math than girls. A high school guidance counselor collects the
math grades from a random sample of 50 boys and another random sample of 50 girls. The guidance
counselor then tested the hypothesis H0 u1-u2=0 against the one-tail alternative and found P=.35.
Which is true? - correct answer ✔✔NONE OF THE ABOVE
A truck company wants on-time delivery for 98% of the parts they order from a metal manufacturing
plant. They have been ordering from a particular steel company but will switch to a new cheaper
manufacturer unless there is evidence that this new manufacturer cannot meet the 98% on time goal. As
a test the truck company purchases a random sample of metal parts from the cheaper manufacturer,
and then determines if these parts were delivered on time. Which hypothesis should they test? - correct
answer ✔✔H0: p=.98
HA: P<.98
Food inspectors need to estimate the level of contaminants in food products packaged at a certain
factory. Intial tests were based on a small sample but now the inspectors double the sample size for a
follow-up test. The main purpose of the larger sample is to do what? - correct answer ✔✔Decrease the
standard deviation of the sampling model.
Which is true about a 99% confidence interval based on a given sample? - correct answer ✔✔III. The
interval is wider than a 95% confidence interval would be.
In an experiment, the primary purpose of blinding is to reduce what? - correct answer ✔✔Bias
Of the following, which is not a critical part of designing a good experiment? - correct answer
✔✔Random selection of subjects
, Suppose that a device advertised to increase a car's gas mileage really does not work. A researcher tests
it on a small fleet of cars (With H0: not effective) and the data results in a P-value of .004. What probably
happens as a result of the experiment? - correct answer ✔✔The researcher rejects H0 making a Type I
error
A researcher is about to test a hypothesis using data from a well designed study. Which is true?
I. A small P-value would be strong evidence against the null hypothesis
II. The researcher can set a higher standard of proof by choosing ὰ=10% instead of 5%
III. If the researcher reduces the alpha level, the researcher reduces the power of the test. - correct
answer ✔✔I & III
A compensation specialist at a technology company wants to asses the competitiveness of the salaries at
his firm. He needs to know the mean salary of the firm's employees. He checks all the employee salaries
using company records and he used his computer to create a 95% confidence interval based on a t-
distribution. This procedure was not appropriate because? - correct answer ✔✔The entire population of
employees was gathered so there is no reason to do inference.
A researcher investigating whether joggers are less likely to get colds than people who do not jog found a
P-value of 3%. What does this mean. - correct answer ✔✔None of the above
Which statement correctly compares T-Distributions to the Normal Distribution? - correct answer ✔✔I. t-
distributions are also mound shaped and symmetric
II. t-distributions are more spread out than the normal distribution.
To plan a budget for the next college year, a college needs to estimate what impact the current economic
downturn might have on student requests for financial aid. Historically, this college has provided aid to
35% of its students. Officials look at a random sample of this year's applications to see what proportion
indicate a need for finacial aid. A 90% confidence interval of (32%, 40%). Could this be used - correct
answer ✔✔YES. Since 35% is in the confidence interval they fail to reject the null hypothesis concluding
that there is not strong evidence of any change in financial aid requests
Absorption rates into the body are important considerations when manufacturing a generic version of a
brand-name drug. A pharmacist read that the absorption rate into the body of a new generic drug (G) is
the same as its brand name counterpart (B). She has a reseracher friend of her run an experiment H0:
correct answers A+ rated
Which of the following is a correct interpretation of a p-value that is NOT very small> - correct answer
✔✔What we saw in the sample data is not surprising, so we fail to reject the null hypothesis.
An old myth claims that boys are better at math than girls. A high school guidance counselor collects the
math grades from a random sample of 50 boys and another random sample of 50 girls. The guidance
counselor then tested the hypothesis H0 u1-u2=0 against the one-tail alternative and found P=.35.
Which is true? - correct answer ✔✔NONE OF THE ABOVE
A truck company wants on-time delivery for 98% of the parts they order from a metal manufacturing
plant. They have been ordering from a particular steel company but will switch to a new cheaper
manufacturer unless there is evidence that this new manufacturer cannot meet the 98% on time goal. As
a test the truck company purchases a random sample of metal parts from the cheaper manufacturer,
and then determines if these parts were delivered on time. Which hypothesis should they test? - correct
answer ✔✔H0: p=.98
HA: P<.98
Food inspectors need to estimate the level of contaminants in food products packaged at a certain
factory. Intial tests were based on a small sample but now the inspectors double the sample size for a
follow-up test. The main purpose of the larger sample is to do what? - correct answer ✔✔Decrease the
standard deviation of the sampling model.
Which is true about a 99% confidence interval based on a given sample? - correct answer ✔✔III. The
interval is wider than a 95% confidence interval would be.
In an experiment, the primary purpose of blinding is to reduce what? - correct answer ✔✔Bias
Of the following, which is not a critical part of designing a good experiment? - correct answer
✔✔Random selection of subjects
, Suppose that a device advertised to increase a car's gas mileage really does not work. A researcher tests
it on a small fleet of cars (With H0: not effective) and the data results in a P-value of .004. What probably
happens as a result of the experiment? - correct answer ✔✔The researcher rejects H0 making a Type I
error
A researcher is about to test a hypothesis using data from a well designed study. Which is true?
I. A small P-value would be strong evidence against the null hypothesis
II. The researcher can set a higher standard of proof by choosing ὰ=10% instead of 5%
III. If the researcher reduces the alpha level, the researcher reduces the power of the test. - correct
answer ✔✔I & III
A compensation specialist at a technology company wants to asses the competitiveness of the salaries at
his firm. He needs to know the mean salary of the firm's employees. He checks all the employee salaries
using company records and he used his computer to create a 95% confidence interval based on a t-
distribution. This procedure was not appropriate because? - correct answer ✔✔The entire population of
employees was gathered so there is no reason to do inference.
A researcher investigating whether joggers are less likely to get colds than people who do not jog found a
P-value of 3%. What does this mean. - correct answer ✔✔None of the above
Which statement correctly compares T-Distributions to the Normal Distribution? - correct answer ✔✔I. t-
distributions are also mound shaped and symmetric
II. t-distributions are more spread out than the normal distribution.
To plan a budget for the next college year, a college needs to estimate what impact the current economic
downturn might have on student requests for financial aid. Historically, this college has provided aid to
35% of its students. Officials look at a random sample of this year's applications to see what proportion
indicate a need for finacial aid. A 90% confidence interval of (32%, 40%). Could this be used - correct
answer ✔✔YES. Since 35% is in the confidence interval they fail to reject the null hypothesis concluding
that there is not strong evidence of any change in financial aid requests
Absorption rates into the body are important considerations when manufacturing a generic version of a
brand-name drug. A pharmacist read that the absorption rate into the body of a new generic drug (G) is
the same as its brand name counterpart (B). She has a reseracher friend of her run an experiment H0:
