QBA STUDY GUIDE 2025/2026 QUESTIONS AND SOLUTION
RATED A+
✔✔What is the purpose of the Regression Equation? - ✔✔Allows you to predict Y
values based on known X values
✔✔What P (probability) value tells us the relationship is significant? - ✔✔<= .05
✔✔Linear relationships can be... - ✔✔Either positive or negative
✔✔What is the purpose of simple linear regression? - ✔✔To predict one variable based
on a known variable and correlation
✔✔If the correlation coefficient between 2 variables is -0.89, what is the strength of the
correlation? - ✔✔Very strong negative correlation
✔✔Pearson's Correlation is used to analyze the relationship between what kind of
variables? - ✔✔Quantitative
✔✔What is correlation? - ✔✔How much the change in 1 variable is related to a change
in another variable
✔✔What does it mean when we say that the tails of the normal curve are asymptotic to
the x axis? - ✔✔The tails get closer and closer to the x axis but never touch it.
✔✔What are the parameters of the standard normal distribution? - ✔✔Mean = 0,
Standard Deviation = 1
✔✔What does the symbol µ represent? - ✔✔Population mean
✔✔What does the symbol s2 represent? - ✔✔Sample Variance
✔✔What is the correct interpretation of the variance? - ✔✔On average, what a
consumer is willing to pay differs from the mean of $15 by 25 squared dollars.
✔✔What is the correct interpretation of the standard deviation? - ✔✔On average, what
a consumer is willing to pay differs from the mean of $15 by $5.
✔✔The mean of $15 is a __________________. - ✔✔Sample statistic
✔✔What is the population? - ✔✔All consumers
✔✔What is the sample? - ✔✔100 consumers
, ✔✔The United States government conducts a census every 10 years. They collect
information from every single household in America to determine the population of the
country. During the last census, they found that 14.5% of the country is 65 years or
older. - ✔✔population parameter.
✔✔The 28.56% - ✔✔sample statistic.
✔✔What is the population? - ✔✔All Ohio customer
✔✔Amazon wants to determine if how many of their Ohio customers are part of the
'Subscribe & Save' program. They take a sample of 15 customers from each zip code in
Ohio (for a total of 11,890 customers). They find that 28.56% of those customers have
received a 'Subscribe & Save' delivery in the past 3 months. - ✔✔11,890 customers
✔✔What does the symbol σ represent? - ✔✔Population standard deviation
✔✔Which of the following is NOT a characteristic of the normal distribution? - ✔✔It
refers to sample data
✔✔Based on the empirical rule ________ percent of the observations will be contained
within 1 standard deviations around the arithmetic mean, ________ percent of the
observations will be contained within 2 standard deviations around the arithmetic mean,
and ________ percent of the observations will be contained within 3 standard
deviations around the arithmetic mean. - ✔✔about 68, about 95, and about 99
✔✔What is the correct interpretation of the variance? - ✔✔It represents the average
difference from a data point to the mean, in squared units.
✔✔What is the correct interpretation of the standard deviation? - ✔✔It represents the
average difference from a data point to the mean.
✔✔"33.2%" is a - ✔✔sample statistic
✔✔Of the U.S. adult population, 36% has an allergy. A sample of 1200 randomly
selected adults resulted in 33.2% reporting an allergy. - ✔✔population parameter
✔✔Which set of values has no specific relationship with each other? - ✔✔Mode and
Sum
✔✔Why is the standard deviation a better measure of spread than range? -
✔✔Standard deviation can predict the percentage of values that fall in a given interval
RATED A+
✔✔What is the purpose of the Regression Equation? - ✔✔Allows you to predict Y
values based on known X values
✔✔What P (probability) value tells us the relationship is significant? - ✔✔<= .05
✔✔Linear relationships can be... - ✔✔Either positive or negative
✔✔What is the purpose of simple linear regression? - ✔✔To predict one variable based
on a known variable and correlation
✔✔If the correlation coefficient between 2 variables is -0.89, what is the strength of the
correlation? - ✔✔Very strong negative correlation
✔✔Pearson's Correlation is used to analyze the relationship between what kind of
variables? - ✔✔Quantitative
✔✔What is correlation? - ✔✔How much the change in 1 variable is related to a change
in another variable
✔✔What does it mean when we say that the tails of the normal curve are asymptotic to
the x axis? - ✔✔The tails get closer and closer to the x axis but never touch it.
✔✔What are the parameters of the standard normal distribution? - ✔✔Mean = 0,
Standard Deviation = 1
✔✔What does the symbol µ represent? - ✔✔Population mean
✔✔What does the symbol s2 represent? - ✔✔Sample Variance
✔✔What is the correct interpretation of the variance? - ✔✔On average, what a
consumer is willing to pay differs from the mean of $15 by 25 squared dollars.
✔✔What is the correct interpretation of the standard deviation? - ✔✔On average, what
a consumer is willing to pay differs from the mean of $15 by $5.
✔✔The mean of $15 is a __________________. - ✔✔Sample statistic
✔✔What is the population? - ✔✔All consumers
✔✔What is the sample? - ✔✔100 consumers
, ✔✔The United States government conducts a census every 10 years. They collect
information from every single household in America to determine the population of the
country. During the last census, they found that 14.5% of the country is 65 years or
older. - ✔✔population parameter.
✔✔The 28.56% - ✔✔sample statistic.
✔✔What is the population? - ✔✔All Ohio customer
✔✔Amazon wants to determine if how many of their Ohio customers are part of the
'Subscribe & Save' program. They take a sample of 15 customers from each zip code in
Ohio (for a total of 11,890 customers). They find that 28.56% of those customers have
received a 'Subscribe & Save' delivery in the past 3 months. - ✔✔11,890 customers
✔✔What does the symbol σ represent? - ✔✔Population standard deviation
✔✔Which of the following is NOT a characteristic of the normal distribution? - ✔✔It
refers to sample data
✔✔Based on the empirical rule ________ percent of the observations will be contained
within 1 standard deviations around the arithmetic mean, ________ percent of the
observations will be contained within 2 standard deviations around the arithmetic mean,
and ________ percent of the observations will be contained within 3 standard
deviations around the arithmetic mean. - ✔✔about 68, about 95, and about 99
✔✔What is the correct interpretation of the variance? - ✔✔It represents the average
difference from a data point to the mean, in squared units.
✔✔What is the correct interpretation of the standard deviation? - ✔✔It represents the
average difference from a data point to the mean.
✔✔"33.2%" is a - ✔✔sample statistic
✔✔Of the U.S. adult population, 36% has an allergy. A sample of 1200 randomly
selected adults resulted in 33.2% reporting an allergy. - ✔✔population parameter
✔✔Which set of values has no specific relationship with each other? - ✔✔Mode and
Sum
✔✔Why is the standard deviation a better measure of spread than range? -
✔✔Standard deviation can predict the percentage of values that fall in a given interval
