ISDS 361A COMPREHENSIVE 2026 QUESTIONS AND
SOLUTIONS RATED A+
✔✔How to locate Q1, Q2, and Q3 in box plot - ✔✔Q1: lower quartile
Q2: middle quartile (median)
Q3: upper quartile
✔✔How to compute Inter-Quartile Range (IQR) - ✔✔Q3-Q1
✔✔How to compute lower and upper limits for outlier detections - ✔✔Lower range limit
= Q1 - (1.5* IQR). Essentially this is 1.5 times the inner quartile range subtracting from
your 1st quartile.
Higher range limit = Q3 + (1.5*IQR) This is 1.5 times IQR+ quartile 3.
✔✔EXCEL FORMULAS - ✔✔Average: =AVERAGE()
Median: =MEDIAN()
Mode: MODE.SINGL(), MODE.MULT()
Range: =MAX()-MIN()
=QUARTILE.EXC
=VAR.P, VAR.S
standard dev: STDEV.S(), STDEV.P()
✔✔Range - ✔✔simplest measure of variability.
-largest value-smallest value
✔✔IQR - ✔✔a measure of variability that overcomes the dependency on extreme
values
-uses the middle 50% of data.
✔✔Standard Deviation - ✔✔defined to be the positive square root of the variance.
-most efficient since it uses all the data.
✔✔Coefficient of variation - ✔✔indicates how large the standard deviation is relative to
the mean.
-usually expressed as a percentage.
✔✔population mean - ✔✔Mu (μ)
✔✔population standard deviation - ✔✔sigma (σ)
✔✔sample mean - ✔✔x̅
, ✔✔sample standard deviation - ✔✔S
✔✔Z-score - ✔✔can be interpreted as the number of standard deviations x is from the
mean (x bar).
-measures location of particular value in data, relative to mean.
z= (value - mean)/standard deviation
✔✔The Empirical Rule - ✔✔applies to when the distribution is approximately normal.
-symmetric & unimodal
-mound shaped (bell)
-if beyond 3 and -3 it is outlier.
-DO NOT USE if distribution is skewed and multimodal.
✔✔Chebysheff's Theorem - ✔✔applies to the distribution of any shape.
-not as precise
-enables us to make statements about the proportion of data values that must be within
a specified number of standard deviations of the mean.
= 1-(1/z^2)
✔✔ Statistics - ✔✔a way of getting information
-helps make valid decisions.
✔✔Data - ✔✔the facts and figures collected, analyzed, and summarized for
presentation and interpretation
✔✔information - ✔✔Data converted into a meaningful and useful context
✔✔business decisions - ✔✔these include strategic decisions (very important ones
which can affect the overall success of the business)
✔✔Business Analytics - ✔✔the scientific process of transforming data into insight for
making better business decisions.
✔✔Data science - ✔✔Managing and analyzing massive sets of data for purposes such
as target marketing, trend analysis, and the creation of individually tailored products and
services.
✔✔Descriptive statistics - ✔✔Data that is summarized and presented in a form that is
easy for the reader to understand.
-statistical information in newspapers, magazines, company reports, and other
publications
--summaries of data which may be tabular, graphical, or numerical.
SOLUTIONS RATED A+
✔✔How to locate Q1, Q2, and Q3 in box plot - ✔✔Q1: lower quartile
Q2: middle quartile (median)
Q3: upper quartile
✔✔How to compute Inter-Quartile Range (IQR) - ✔✔Q3-Q1
✔✔How to compute lower and upper limits for outlier detections - ✔✔Lower range limit
= Q1 - (1.5* IQR). Essentially this is 1.5 times the inner quartile range subtracting from
your 1st quartile.
Higher range limit = Q3 + (1.5*IQR) This is 1.5 times IQR+ quartile 3.
✔✔EXCEL FORMULAS - ✔✔Average: =AVERAGE()
Median: =MEDIAN()
Mode: MODE.SINGL(), MODE.MULT()
Range: =MAX()-MIN()
=QUARTILE.EXC
=VAR.P, VAR.S
standard dev: STDEV.S(), STDEV.P()
✔✔Range - ✔✔simplest measure of variability.
-largest value-smallest value
✔✔IQR - ✔✔a measure of variability that overcomes the dependency on extreme
values
-uses the middle 50% of data.
✔✔Standard Deviation - ✔✔defined to be the positive square root of the variance.
-most efficient since it uses all the data.
✔✔Coefficient of variation - ✔✔indicates how large the standard deviation is relative to
the mean.
-usually expressed as a percentage.
✔✔population mean - ✔✔Mu (μ)
✔✔population standard deviation - ✔✔sigma (σ)
✔✔sample mean - ✔✔x̅
, ✔✔sample standard deviation - ✔✔S
✔✔Z-score - ✔✔can be interpreted as the number of standard deviations x is from the
mean (x bar).
-measures location of particular value in data, relative to mean.
z= (value - mean)/standard deviation
✔✔The Empirical Rule - ✔✔applies to when the distribution is approximately normal.
-symmetric & unimodal
-mound shaped (bell)
-if beyond 3 and -3 it is outlier.
-DO NOT USE if distribution is skewed and multimodal.
✔✔Chebysheff's Theorem - ✔✔applies to the distribution of any shape.
-not as precise
-enables us to make statements about the proportion of data values that must be within
a specified number of standard deviations of the mean.
= 1-(1/z^2)
✔✔ Statistics - ✔✔a way of getting information
-helps make valid decisions.
✔✔Data - ✔✔the facts and figures collected, analyzed, and summarized for
presentation and interpretation
✔✔information - ✔✔Data converted into a meaningful and useful context
✔✔business decisions - ✔✔these include strategic decisions (very important ones
which can affect the overall success of the business)
✔✔Business Analytics - ✔✔the scientific process of transforming data into insight for
making better business decisions.
✔✔Data science - ✔✔Managing and analyzing massive sets of data for purposes such
as target marketing, trend analysis, and the creation of individually tailored products and
services.
✔✔Descriptive statistics - ✔✔Data that is summarized and presented in a form that is
easy for the reader to understand.
-statistical information in newspapers, magazines, company reports, and other
publications
--summaries of data which may be tabular, graphical, or numerical.
