Statistics & Probability
Statistical Analysis
Finding the Mean, Median, Mode, and Range of a dataset.
Questions use lists of rolled-die results, test scores, inventory records, CPI tables, and bar/line graphs. Multiple-choice traps include outlier values just outside the plausible range.
What the exam tests
Standard Set Calculations
A list of values is provided and you must identify the mean, median, mode, or range.
Weighted Average Scenarios
Different sets of values are assigned different weights, requiring the weighted average formula.
Accounting Inventory Valuation
Questions on the Weighted Average method to determine the value of shipped or remaining inventory.
Economic Index Problems
Calculations involving the Consumer Price Index (CPI), a weighted average used to measure inflation or deflation.
Table and Graph Interpretation
Data must be extracted from bar or line graphs to determine central tendencies or range components.
Data Aggregation (Mean)
Key rules
- ›Sum all values in the set, then divide by the number of observations.
- ›Formula: X̄ = Σx ÷ n.
Common traps
- !Forgetting to include all values in the sum before dividing.
Ranking and Sorting (Median)
Key rules
- ›Arrange all values from smallest to greatest first.
- ›If the count is odd, the median is the single middle value.
- ›If the count is even, average the two middle values.
Common traps
- !Picking the middle value from an unsorted list.
Frequency Analysis (Mode)
Key rules
- ›The mode is the value that appears most frequently in the set.
- ›A dataset can have more than one mode or no mode at all.
Extremes Subtraction (Range)
Key rules
- ›Range = greatest value − smallest value.
- ›Sort the data first to clearly identify the extremes.
Weighted Formula Application
Key rules
- ›Formula: X̄w = Σ(x × wᵢ) ÷ Σwᵢ.
- ›Multiply each value by its weight, sum the products, then divide by the total weight.
Common traps
- !Dividing by the number of groups instead of the total weight.
Data Filtering
Key rules
- ›Eliminate irrelevant information (names, dates, labels) before calculating.
- ›Isolate only the numerical values needed for the statistic.
Reasonableness Check
Key rules
- ›The mean, median, and mode must all fall between the minimum and maximum values of the set.
- ›Use mental rounding to estimate before calculating to catch errors.
Common traps
- !Accepting an answer outside the range of the dataset.
Try one
A die is rolled five times, producing the results 1, 1, 5, 4, and 6. What is the mean of these results?
Sum all values: 1 + 1 + 5 + 4 + 6 = 17. Divide by the count of 5 results: 17 ÷ 5 = 3.4.
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