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A data analyst is evaluating a dataset to determine the most frequent value among
customer ages. Which measure of central tendency should they use?
A. Mean
B. Median
C. Mode
D. Range
CORRECT ANSWER: C. Mode
Rationale: The mode identifies the most frequently occurring value in a dataset.
Mean is the average, median is the middle value, and range measures spread,
not central tendency.
In a hypothesis test, a p-value of 0.03 is calculated at a 0.05 significance level.
What is the correct decision?
A. Accept the null hypothesis
B. Reject the null hypothesis
C. Fail to reject the null hypothesis
D. Conclude the test is inconclusive
CORRECT ANSWER: B. Reject the null hypothesis
Rationale: Since p-value (0.03) < alpha (0.05), the result is statistically
significant, leading to rejection of the null hypothesis.
,Which type of analytics answers the question, “What happened?” by summarizing
historical data?
A. Predictive analytics
B. Prescriptive analytics
C. Diagnostic analytics
D. Descriptive analytics
CORRECT ANSWER: D. Descriptive analytics
Rationale: Descriptive analytics focuses on summarizing past data. Predictive
forecasts future events, diagnostic explains why, and prescriptive recommends
actions.
A company wants to predict which customers are likely to churn based on past
behavior. Which machine learning technique is most appropriate?
A. Linear regression
B. K-means clustering
C. Logistic regression
D. Principal component analysis
CORRECT ANSWER: C. Logistic regression
Rationale: Logistic regression is used for binary classification (churn vs. non-
churn). Linear regression predicts continuous values, clustering groups data,
and PCA reduces dimensionality.
The standard deviation of a sample measures:
A. The central location of data
B. The most common value in the data
C. The spread of data around the mean
D. The difference between maximum and minimum
,CORRECT ANSWER: C. The spread of data around the mean
Rationale: Standard deviation quantifies the average distance of data points
from the mean, indicating variability or dispersion.
A researcher finds a correlation coefficient of -0.85 between study time and
number of errors on a test. What does this indicate?
A. More study time leads to more errors
B. Less study time leads to fewer errors
C. Strong negative linear relationship
D. No relationship between variables
CORRECT ANSWER: C. Strong negative linear relationship
Rationale: A correlation of -0.85 is close to -1, indicating a strong negative
linear relationship: as study time increases, errors decrease.
In a data analytics lifecycle, which phase involves cleaning, transforming, and
validating raw data?
A. Data discovery
B. Data preparation
C. Model planning
D. Operationalization
CORRECT ANSWER: B. Data preparation
Rationale: Data preparation (or preprocessing) includes cleaning, transforming,
and validating data to make it suitable for analysis.
A boxplot shows that the median is closer to the lower quartile and the upper
whisker is longer than the lower whisker. This distribution is:
A. Symmetric
, B. Negatively skewed
C. Positively skewed
D. Uniform
CORRECT ANSWER: C. Positively skewed
Rationale: In positive skew, the median is left of center, and the upper tail (right
side) is longer, pulling the mean above the median.
Which probability distribution is best for modeling the number of customer arrivals
per minute at a service desk, assuming arrivals occur independently at a constant
average rate?
A. Binomial distribution
B. Normal distribution
C. Poisson distribution
D. Exponential distribution
CORRECT ANSWER: C. Poisson distribution
Rationale: Poisson distribution models count of events in fixed interval with
constant average rate and independent occurrences.
A data scientist uses a confusion matrix to evaluate a classification model. What
does the true positive rate (sensitivity) represent?
A. Correctly predicted negatives / total actual negatives
B. Correctly predicted positives / total actual positives
C. Correctly predicted positives / total predicted positives
D. Correctly predicted negatives / total predicted negatives
CORRECT ANSWER: B. Correctly predicted positives / total actual positives
Rationale: Sensitivity (recall) = TP / (TP+FN), measuring proportion of actual
positives correctly identified.