STT 231 EXAM 2 QUESTIONS &
ANSWERS
Suppose that you select a random sample of people and ask for their politicalviewpoint
and whether or not they support a particular policy proposal. Supposethat 60% of
liberals support the proposal, compared to 35% of moderates and25% of conservatives.
For which sample size will this result provide strongerevidence that the three political
groups do not have the same populationproportions who support the proposal -
ANSWERSample size of 200 for each group
Suppose a laboratory tested the amount (in milligrams) of cholesterol per egg ina
random sample of 30 chicken eggs in a poultry farm. For each of the following
questions, indicate the appropriate inference procedure
How old, on average, is a chicken egg in this farm?
i. z-interval for a proportion, 𝜋
ii. z-test for a proportion, 𝜋
iii. t-interval for a mean, 𝝁
iv. t-test for a mean, 𝜇 - ANSWERiii. t-interval for a mean, 𝝁
Suppose a laboratory tested the amount (in milligrams) of cholesterol per egg ina
random sample of 30 chicken eggs in a poultry farm. For each of the following
questions, indicate the appropriate inference procedure
Do 75% of chicken eggs in this farm contain less than 230 milligrams of cholesterol?
i. z-interval for a proportion, 𝜋
ii. z-test for a proportion, 𝝅
iii. t-interval for a mean, 𝜇
iv. t-test for a mean, 𝜇 - ANSWERii. z-test for a proportion, 𝝅
Suppose a laboratory tested the amount (in milligrams) of cholesterol per egg ina
random sample of 30 chicken eggs in a poultry farm. For each of the following
questions, indicate the appropriate inference procedure
What percentage of chicken eggs in this farm contain fewer than 235milligrams of
cholesterol?
i. z-interval for a proportion, 𝝅
ii. z-test for a proportion, 𝜋
iii. t-interval for a mean, 𝜇
iv. t-test for a mean, 𝜇 - ANSWERi. z-interval for a proportion, 𝝅
, Suppose a laboratory tested the amount (in milligrams) of cholesterol per egg ina
random sample of 30 chicken eggs in a poultry farm. For each of the following
questions, indicate the appropriate inference procedure
How much cholesterol, on average, is contained in a chicken egg fromthis farm?
i. z-interval for a proportion, 𝜋
ii. z-test for a proportion, 𝜋
iii. t-interval for a mean, 𝝁
iv. t-test for a mean, 𝜇 - ANSWERiii. t-interval for a mean, 𝝁
Suppose a laboratory tested the amount (in milligrams) of cholesterol per egg ina
random sample of 30 chicken eggs in a poultry farm. For each of the following
questions, indicate the appropriate inference procedure
What percentage of chicken eggs in this farm have been tested at leastonce in the past
10 days?
i. z-interval for a proportion, 𝝅
ii. z-test for a proportion, 𝜋
iii. t-interval for a mean, 𝜇
iv. t-test for a mean, 𝜇 - ANSWERi. z-interval for a proportion, 𝝅
____________ draws a conclusion (i.e., infers something) about a population based on
a sample statistic - ANSWERstatistical inference
A ____________ estimates the value of a parameter with a range ofvalues -
ANSWERconfidence interval
A confidence interval estimates the value of a parameter with a range of values.
A ________, 𝜋, can be estimated with a z-interval.
A ________, 𝜇, can be estimated with a t-interval - ANSWERpopulation proportion
population mean
Consider a confidence interval for an unknown population parameter. Assuming
that all else remains unchanged, which of the following changes would cause
the confidence interval to become narrower?
a. Larger sample size
b. Larger confidence interval
c. Both of the above
d. Neither of the above - ANSWERa. Larger sample size
A researcher is conducting a randomized, placebo-controlled experiment to test the
hypotheses 𝐻o : 𝜋 = 0.4 vs 𝐻a : 𝜋 > 0.4, where 𝜋 = the population proportion of all
ANSWERS
Suppose that you select a random sample of people and ask for their politicalviewpoint
and whether or not they support a particular policy proposal. Supposethat 60% of
liberals support the proposal, compared to 35% of moderates and25% of conservatives.
For which sample size will this result provide strongerevidence that the three political
groups do not have the same populationproportions who support the proposal -
ANSWERSample size of 200 for each group
Suppose a laboratory tested the amount (in milligrams) of cholesterol per egg ina
random sample of 30 chicken eggs in a poultry farm. For each of the following
questions, indicate the appropriate inference procedure
How old, on average, is a chicken egg in this farm?
i. z-interval for a proportion, 𝜋
ii. z-test for a proportion, 𝜋
iii. t-interval for a mean, 𝝁
iv. t-test for a mean, 𝜇 - ANSWERiii. t-interval for a mean, 𝝁
Suppose a laboratory tested the amount (in milligrams) of cholesterol per egg ina
random sample of 30 chicken eggs in a poultry farm. For each of the following
questions, indicate the appropriate inference procedure
Do 75% of chicken eggs in this farm contain less than 230 milligrams of cholesterol?
i. z-interval for a proportion, 𝜋
ii. z-test for a proportion, 𝝅
iii. t-interval for a mean, 𝜇
iv. t-test for a mean, 𝜇 - ANSWERii. z-test for a proportion, 𝝅
Suppose a laboratory tested the amount (in milligrams) of cholesterol per egg ina
random sample of 30 chicken eggs in a poultry farm. For each of the following
questions, indicate the appropriate inference procedure
What percentage of chicken eggs in this farm contain fewer than 235milligrams of
cholesterol?
i. z-interval for a proportion, 𝝅
ii. z-test for a proportion, 𝜋
iii. t-interval for a mean, 𝜇
iv. t-test for a mean, 𝜇 - ANSWERi. z-interval for a proportion, 𝝅
, Suppose a laboratory tested the amount (in milligrams) of cholesterol per egg ina
random sample of 30 chicken eggs in a poultry farm. For each of the following
questions, indicate the appropriate inference procedure
How much cholesterol, on average, is contained in a chicken egg fromthis farm?
i. z-interval for a proportion, 𝜋
ii. z-test for a proportion, 𝜋
iii. t-interval for a mean, 𝝁
iv. t-test for a mean, 𝜇 - ANSWERiii. t-interval for a mean, 𝝁
Suppose a laboratory tested the amount (in milligrams) of cholesterol per egg ina
random sample of 30 chicken eggs in a poultry farm. For each of the following
questions, indicate the appropriate inference procedure
What percentage of chicken eggs in this farm have been tested at leastonce in the past
10 days?
i. z-interval for a proportion, 𝝅
ii. z-test for a proportion, 𝜋
iii. t-interval for a mean, 𝜇
iv. t-test for a mean, 𝜇 - ANSWERi. z-interval for a proportion, 𝝅
____________ draws a conclusion (i.e., infers something) about a population based on
a sample statistic - ANSWERstatistical inference
A ____________ estimates the value of a parameter with a range ofvalues -
ANSWERconfidence interval
A confidence interval estimates the value of a parameter with a range of values.
A ________, 𝜋, can be estimated with a z-interval.
A ________, 𝜇, can be estimated with a t-interval - ANSWERpopulation proportion
population mean
Consider a confidence interval for an unknown population parameter. Assuming
that all else remains unchanged, which of the following changes would cause
the confidence interval to become narrower?
a. Larger sample size
b. Larger confidence interval
c. Both of the above
d. Neither of the above - ANSWERa. Larger sample size
A researcher is conducting a randomized, placebo-controlled experiment to test the
hypotheses 𝐻o : 𝜋 = 0.4 vs 𝐻a : 𝜋 > 0.4, where 𝜋 = the population proportion of all
