STT 231 Exam Questions and Answers | 2026
Update | 100% Correct
What is a confidence interval and why do we use it?
The probability of an answer being within a certain range. we use this because
sometimes we can not be exact with what the answer is.
What pieces of information does a one-proportion confidence interval give us?
A range of plausible values for a population parameter, and a level for such range
What sample statistic does a one-proportion confidence interval use?
pi-hat standard error to create interval of plausible values for the parameter π
How can we plot this in R?
Use prop.test and putting in the confidence interval given
Confidence intervals that have a higher ____________ _______ are ________
then those with lower confidence levels
Confidence level, wider
The smaller the confidence interval (assuming same survey results) results in
a ________ interval
narrower
, The bigger the confidence interval (assuming same survey results) results in a
________ interval
wider
The decimal value from a confidence interval represents what?
The percentage of likelihood the study falls into
Increased confidence results in ______ precise range resulting in a _____
interval
less, wider
decreased confidence results in ______ precise range resulting in a _____
interval
greater, narrower
What pieces of information does a one-mean confidence interval give us?
A range of plausible values for a population parameter, and a level for such range
What sample statistic does a one-mean confidence interval use?
x-bar standard error to create interval of plausible values for the parameter µ
How can we get one-mean confidence interval in R?
t.test
Update | 100% Correct
What is a confidence interval and why do we use it?
The probability of an answer being within a certain range. we use this because
sometimes we can not be exact with what the answer is.
What pieces of information does a one-proportion confidence interval give us?
A range of plausible values for a population parameter, and a level for such range
What sample statistic does a one-proportion confidence interval use?
pi-hat standard error to create interval of plausible values for the parameter π
How can we plot this in R?
Use prop.test and putting in the confidence interval given
Confidence intervals that have a higher ____________ _______ are ________
then those with lower confidence levels
Confidence level, wider
The smaller the confidence interval (assuming same survey results) results in
a ________ interval
narrower
, The bigger the confidence interval (assuming same survey results) results in a
________ interval
wider
The decimal value from a confidence interval represents what?
The percentage of likelihood the study falls into
Increased confidence results in ______ precise range resulting in a _____
interval
less, wider
decreased confidence results in ______ precise range resulting in a _____
interval
greater, narrower
What pieces of information does a one-mean confidence interval give us?
A range of plausible values for a population parameter, and a level for such range
What sample statistic does a one-mean confidence interval use?
x-bar standard error to create interval of plausible values for the parameter µ
How can we get one-mean confidence interval in R?
t.test
