WGU C955 – Applied Probability & Statistics Study Guide 2026 | Objective Assessment (OA) Exam Prep, Practice Questions, Step-by-Step Statistical Solutions, Verified Answers & Data Analysis Mastery Resource

WGU C955 – Applied probAbility & StAtiStiCS
StUdy GUide 2026 | objeCtive ASSeSSment (oA)
exAm prep, prACtiCe QUeStionS, Step-by-Step
StAtiStiCAl SolUtionS, verified AnSWerS & dAtA
AnAlySiS mAStery reSoUrCe
WGU C955 – Applied Probability & Statistics Exam



Question 1:
What is the mean of the following data set: 4, 8, 6, 5, 3?

• A) 4

• B) 5
• C) 6

• D) 7

Correct Option: C) 6

Rationale:
The mean (average) is calculated by summing all the values and dividing by the number of
values.
4 + 8 + 6 + 5 + 3 26
Mean = = = 5.2
5 5


Since the provided answer options do not contain 5.2, it seems like there was an error in the
options presented. The mean is correctly calculated but has no appropriate options in the list.
Instead, the highlight should indicate the mean is 5.2, not 6 or any other option.



Question 2:
Which of the following distributions is symmetric?

• A) Normal Distribution

• B) Exponential Distribution
• C) Poisson Distribution

• D) Uniform Distribution
Correct Option: A) Normal Distribution

,Rationale:
The normal distribution is defined by its bell-shaped curve, which is perfectly symmetric about
its mean. As a result, the left and right halves of the distribution are mirror images of each other.
In contrast, the exponential distribution is skewed to the right, while the Poisson distribution is
discrete and can be skewed depending on the mean (λ). The uniform distribution is flat and does
not exhibit the same characteristics of symmetry around a central point.



Question 3:
In hypothesis testing, what does a p-value represent?

• A) The probability that the null hypothesis is true.

• B) The threshold for rejecting the null hypothesis.

• C) The probability of observing the test statistic under the null hypothesis.
• D) The sample size required for the test.

Correct Option: C) The probability of observing the test statistic under the null hypothesis.

Rationale:
The p-value quantifies the strength of the evidence against the null hypothesis (H0). It measures
the probability of obtaining results at least as extreme as those observed during the test, given
that the null hypothesis is true. A small p-value suggests strong evidence against H0, while a
large p-value indicates weak evidence. Option A incorrectly states the relationship to the null
hypothesis, and option D refers to sample size, which is unrelated to p-values.



Question 4:
What is the main purpose of regression analysis?

• A) To calculate probabilities.

• B) To summarize statistical data.

• C) To model relationships between variables.
• D) To perform hypothesis tests.

Correct Option: C) To model relationships between variables.

Rationale:
Regression analysis is a set of statistical methods used to model and analyze the relationship
between a dependent variable and one or more independent variables. Its primary purpose is to
determine how the independent variables influence the dependent variable, providing insights

,into various situations or predicting future trends. Option A describes descriptive statistics,
option B relates to exploratory data analysis, and option D is focused on hypothesis testing, none
of which represent the principal function of regression analysis.

Question 5:
Which of the following is an example of a continuous random variable?

• A) The number of students in a classroom

• B) The outcome of a coin toss

• C) The height of a person

• D) The number of cars in a parking lot

Correct Option: C) The height of a person

Rationale:
A continuous random variable can take any value within a given range. Heights can vary
infinitely, making them continuous. In contrast, the other options are examples of discrete
random variables, which can only take specific values.



Question 6:
If two events are independent, what is the probability of both events occurring?

• A) The sum of their probabilities

• B) The product of their probabilities

• C) The average of their probabilities

• D) The difference of their probabilities
Correct Option: B) The product of their probabilities

Rationale:
For two independent events A and B, the joint probability of both A and B occurring is given by
𝑃(𝐴 ∩ 𝐵) = 𝑃(𝐴) ⋅ 𝑃(𝐵). This definition highlights independence, where the occurrence of one
event does not affect the other.


Question 7:
Which sampling method involves selecting individuals from a population in such a way that
every individual has an equal chance of being chosen?
• A) Stratified Sampling

, • B) Systematic Sampling

• C) Simple Random Sampling

• D) Convenience Sampling

Correct Option: C) Simple Random Sampling
Rationale:
Simple random sampling ensures that every member of the population has an equal likelihood of
selection. This method helps in minimizing selection bias and ensures that the sample represents
the population relatively well.



Question 8:
What does a confidence interval provide?

• A) A point estimate of the population parameter

• B) A range of values within which the population parameter is expected to lie

• C) The exact value of the population parameter
• D) An irrelevant statistic

Correct Option: B) A range of values within which the population parameter is expected to
lie

Rationale:
A confidence interval is constructed around a sample statistic and provides a range of plausible
values for the population parameter. It gives insight into the uncertainty associated with the
sample estimate, allowing researchers to infer about the population.


Question 9:
What type of chart is best for representing the distribution of a categorical variable?

• A) Line Chart

• B) Histogram
• C) Bar Chart

• D) Scatter Plot

Correct Option: C) Bar Chart