WGU C207 Data-Driven Decision Making Exam Review 2026/2027 Ultimate Exam Prep Guide: Extensive Practice Tests, Complete Test Bank, and Detailed Study Review Notes

A polling organization surveys a random sample of 1,500 registered voters and uses the findings to estimate the preferences of all registered voters in the country. This process is best described as: A. Descriptive statistics B. Inferential statistics C. Data operationalization D. Deterministic modeling Correct Answer: B. Inferential statistics Rationale: Inferential statistics use information obtained from a sample to estimate, predict, or draw conclusions about a larger population. Descriptive statistics would summarize only the 1,500 surveyed voters without extending conclusions beyond them. Operationalization concerns how variables are measured, while deterministic modeling assumes outcomes can be predicted without probabilistic uncertainty. Question 2 A researcher observes that an employee wears a blue shirt on two consecutive Tuesdays. She concludes that the employee always wears blue on Tuesdays. Which methodological weakness most directly undermines this conclusion? A. The variable was poorly operationalized B. The sample contained too few observations C. Participants demonstrated response bias D. The observations were not blinded Correct Answer: B. The sample contained too few observations Rationale: Two observations are insufficient to establish a reliable pattern of behavior. A small sample is highly vulnerable to chance and may not represent the employee’s usual clothing choices. Operationalization is not the primary problem because shirt color was directly observed. Response bias does not apply because no participant answered questions, and blinding would not resolve the lack of adequate data. Question 3 A delivery company reports a 0.90 probability that a package arrives within three days and a 0.75 probability that it becomes wet. The probability that a package both arrives within three days and becomes wet is 0.70. What is the probability that a package experiences at least one of these outcomes? A. 0.65 B. 0.70 C. 0.95 D. 1.65 Correct Answer: C. 0.95 Rationale: Use the addition rule for a union: P(A B) = P(A) + P(B) − P(A ∩ B) Therefore: 0.90 + 0.75 − 0.70 = 0.95 The intersection must be subtracted because packages experiencing both outcomes were counted twice. Question 4 Employee productivity scores are approximately normally distributed with a mean of 100 and a standard deviation of 12. Approximately what percentage of employees score between 76 and 124? A. 68.3% B. 90.0% C. 95.4% D. 99.7% Correct Answer: C. 95.4% Rationale: Scores of 76 and 124 are two standard deviations below and above the mean: 100 ± 2(12) = 76 to 124 Under the empirical rule, approximately 95.4% of observations in a normal distribution lie within two standard deviations of the mean. About 68.3% lie within one standard deviation, and 99.7% lie within three. Question 5 A physician wants to estimate patients’ risk of myocardial infarction. Instead of measuring blood pressure, cholesterol, smoking history, or other recognized risk factors, the physician records each patient’s hair length. Which flaw is most evident? A. Inadequate operationalization B. Response bias C. Failure to blind participants D. Insufficient statistical power Correct Answer: A. Inadequate operationalization Rationale: Operationalization requires translating a concept into a variable that meaningfully measures it. Hair length is not a valid measure of myocardial infarction risk, whereas blood pressure, cholesterol, age, and smoking history are relevant indicators. A large sample would not correct this validity problem. Question 6 A manager records the following number of customer complaints over ten days: 9, 7, 23, 20, 4, 6, 26, 5, 21, 14 What is the mean number of complaints per day? A. 10.0 B. 12.5 C. 13.5 D. 15.0 Correct Answer: C. 13.5 Rationale: The mean equals the sum of all observations divided by the number of observations. The ten values total 135, so: 135 ÷ 10 = 13.5 Therefore, the mean number of complaints per day is 13.5. Question 7 A national retail company analyzes household-income data to identify promising markets, studies website traffic to select advertising platforms, and examines historical corporate performance to forecast investment trends. Which proposed activity is least appropriately classified as a standard business application of statistics? A. Identifying advertising platforms with the greatest potential audience reach B. Segmenting potential customers according to household income C. Forecasting corporate investment trends using historical performance D. Predicting individual directors’ votes primarily from their political voting behavior Correct Answer: D. Predicting individual directors’ votes primarily from their political voting behavior Rationale: Options A, B, and C use statistical evidence to support marketing, customer segmentation, and financial forecasting—common business functions. Option D focuses primarily on predicting political behavior rather than analyzing a conventional business outcome. Question 8 Two investment funds have the same average annual return. Fund A’s returns are tightly clustered around the average, while Fund B’s returns vary widely from year to year. Which measure best quantifies this difference? A. Median B. Standard deviation C. Mode D. Percentile rank Correct Answer: B. Standard deviation Rationale: Standard deviation measures the typical dispersion of observations around their mean. A larger standard deviation indicates greater variability and, in an investment context, often greater volatility. The median identifies the middle value, the mode identifies the most frequent value, and a percentile rank shows relative position. Question 9 The probability of snow tomorrow is 0.80. If it does not snow, the probability that Todd walks to the store is 0.60. What is the probability that it does not snow and Todd walks to the store? A. 0.08 B. 0.12 C. 0.48 D. 0.60 Correct Answer: B. 0.12 Rationale: The probability of no snow is: 1 − 0.80 = 0.20 The joint probability is: P(no snow) × P(walk | no snow) Therefore: 0.20 × 0.60 = 0.12 Question 10 For the ordered dataset below, what is the interquartile range using the median-ofhalves method? 5, 9, 14, 25, 32, 36, 37, 37, 43, 48, 51 A. 18 B. 23 C. 29 D. 46 Correct Answer: C. 29 Rationale: The overall median is 36, which is excluded when dividing the dataset into halves. • Lower half: 5, 9, 14, 25, 32 → Q₁ = 14 • Upper half: 37, 37, 43, 48, 51 → Q₃ = 43 Therefore: IQR = Q₃ − Q₁ = 43 − 14 = 29