OPRE 3360 EXAM ONE QUESTIONS WITH COMPLETE
SOLUTIONS
You randomly pick 3 entire classrooms and survey everyone in
those rooms. What method is this? Hint All from some =
Cluster.
Cluster Sampling
You stand outside a store and ask the first 20 people who walk
out. What method is this? Hint You’re just choosing who’s
nearby — no randomness, just ease.
Convenience Sampling
You pick every 10th customer from a checkout line. What
method is this? Hint: n-th person =
Systematic Sampling
You assign a number to every student at your school and
randomly select 50 of them. What method is this?
Hint:Everyone had an equal shot. You used random
selection from the whole list.
Simple Random Sampling
Which of the following is a categorical variable? Hint: If it's a
label
Hair color
, Which of the following is a quantitative variable? Hint:If it’s
a number you can calculate with (add, average),
it’s quantitative.
Test score
You ask people their favorite type of pet. What type of variable
is this?
Categorical
you record the number of hours students studied. What type of
variable is this? Hint: You can average or total them.
Quantitative
Which variable makes sense to take an average of?
Exam score
What is the formula to calculate IQR? Hint: Spread of the
middle 50% of data
Q3 - Q1
What is the rule to identify outliers using IQR? Hint Too low: <
Q1 − 1.5 × IQRToo high: > Q3 + 1.5 × IQR
Anything outside Q1 - 1.5×IQR or Q3 + 1.5×IQR
If Q1 = 20 and Q3 = 40, what is the IQR? HINT : IQR = 40 - 20
SOLUTIONS
You randomly pick 3 entire classrooms and survey everyone in
those rooms. What method is this? Hint All from some =
Cluster.
Cluster Sampling
You stand outside a store and ask the first 20 people who walk
out. What method is this? Hint You’re just choosing who’s
nearby — no randomness, just ease.
Convenience Sampling
You pick every 10th customer from a checkout line. What
method is this? Hint: n-th person =
Systematic Sampling
You assign a number to every student at your school and
randomly select 50 of them. What method is this?
Hint:Everyone had an equal shot. You used random
selection from the whole list.
Simple Random Sampling
Which of the following is a categorical variable? Hint: If it's a
label
Hair color
, Which of the following is a quantitative variable? Hint:If it’s
a number you can calculate with (add, average),
it’s quantitative.
Test score
You ask people their favorite type of pet. What type of variable
is this?
Categorical
you record the number of hours students studied. What type of
variable is this? Hint: You can average or total them.
Quantitative
Which variable makes sense to take an average of?
Exam score
What is the formula to calculate IQR? Hint: Spread of the
middle 50% of data
Q3 - Q1
What is the rule to identify outliers using IQR? Hint Too low: <
Q1 − 1.5 × IQRToo high: > Q3 + 1.5 × IQR
Anything outside Q1 - 1.5×IQR or Q3 + 1.5×IQR
If Q1 = 20 and Q3 = 40, what is the IQR? HINT : IQR = 40 - 20
