STAT 503 Final EXAM Questions with
complete solution 2025/2026
Is a quantitative variable always measured in numbers? - correct answer ✔Yes
Is any measurement that you record from a sample a variable? - correct answer ✔False
What is a statistic? - correct answer ✔The measure that is taken from the whole sample as a summary
of the sample
Sample data skewed to the left, then longer tail is at the... - correct answer ✔Left
What is sensitive to outliers? - correct answer ✔Median
Formula to calculate standard deviation - correct answer ✔s = sqrt(sum(x1-xbar)^2 / n-1)
How to calculate degrees of freedom? - correct answer ✔n-1
What is the first quartile? - correct answer ✔Median of lower half
What is the third quartile - correct answer ✔Median of upper half
What is included in a box plot summary? - correct answer ✔Q0 = minimum
Q1 = median of lower half
Q2 = median
Q3 = median of upper half
, Q5 = maximum
What is the the interquartile range (IQR)? - correct answer ✔Q3 - Q1 (shown inside box plot)
What is an outlier? - correct answer ✔Any data that is Q3 + 1.5IQR or Q1 - 1.5 IQR
When is a phenomenon random? - correct answer ✔When it has uncertain outcomes in a short run
(sample) but show regular distribution in a long run (population)
What is an outcome? - correct answer ✔Observation of a variable
What is a probability model? - correct answer ✔A mathematical description of a random phenomenon
consisting of 2 parts (sample space and way of assigning probability to event)
What is the multiplication rule? (independent) - correct answer ✔P(AB) = P(A) P(B|A) = P(B) P(A|B)
What is the addition rule? (disjoint) - correct answer ✔P(A or B) = P(A) + P(B) - P(AB)
If A and B are disjoint, the must be dependent. - correct answer ✔TRUE
Why is a probability tree diagram used? - correct answer ✔To show multiple variables according to
stages (the order that they happen)
What is written on each segment in a probability tree? - correct answer ✔A conditional probability
What probability is at the end of the branch on a probability tree? - correct answer ✔The product of
the probabilities of the segments of that branch
complete solution 2025/2026
Is a quantitative variable always measured in numbers? - correct answer ✔Yes
Is any measurement that you record from a sample a variable? - correct answer ✔False
What is a statistic? - correct answer ✔The measure that is taken from the whole sample as a summary
of the sample
Sample data skewed to the left, then longer tail is at the... - correct answer ✔Left
What is sensitive to outliers? - correct answer ✔Median
Formula to calculate standard deviation - correct answer ✔s = sqrt(sum(x1-xbar)^2 / n-1)
How to calculate degrees of freedom? - correct answer ✔n-1
What is the first quartile? - correct answer ✔Median of lower half
What is the third quartile - correct answer ✔Median of upper half
What is included in a box plot summary? - correct answer ✔Q0 = minimum
Q1 = median of lower half
Q2 = median
Q3 = median of upper half
, Q5 = maximum
What is the the interquartile range (IQR)? - correct answer ✔Q3 - Q1 (shown inside box plot)
What is an outlier? - correct answer ✔Any data that is Q3 + 1.5IQR or Q1 - 1.5 IQR
When is a phenomenon random? - correct answer ✔When it has uncertain outcomes in a short run
(sample) but show regular distribution in a long run (population)
What is an outcome? - correct answer ✔Observation of a variable
What is a probability model? - correct answer ✔A mathematical description of a random phenomenon
consisting of 2 parts (sample space and way of assigning probability to event)
What is the multiplication rule? (independent) - correct answer ✔P(AB) = P(A) P(B|A) = P(B) P(A|B)
What is the addition rule? (disjoint) - correct answer ✔P(A or B) = P(A) + P(B) - P(AB)
If A and B are disjoint, the must be dependent. - correct answer ✔TRUE
Why is a probability tree diagram used? - correct answer ✔To show multiple variables according to
stages (the order that they happen)
What is written on each segment in a probability tree? - correct answer ✔A conditional probability
What probability is at the end of the branch on a probability tree? - correct answer ✔The product of
the probabilities of the segments of that branch
