WGU C955 – Applied probAbility & StAtiStiCS
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Exam: WGU C955 – Applied Probability & Statistics
Question 1
What is the meaning of a p-value in hypothesis testing?
A) The probability that the null hypothesis is true.
B) The probability of observing the sample data assuming the null hypothesis is true.
C) The level of significance set before conducting the test.
D) The probability of committing a Type II error.
Correct Option: B
Rationale:
The p-value measures the probability of observing the sample data (or something more extreme)
if the null hypothesis is true. It helps to determine whether to reject the null hypothesis. If the p-
value is less than the significance level (e.g., 0.05), it provides evidence against the null
hypothesis.
Question 2
In a normal distribution, what percentage of data falls within one standard deviation of the
mean?
A) 50%
B) 68%
C) 75%
D) 95%
Correct Option: B
Rationale:
In a normal distribution, approximately 68% of the data points fall within one standard deviation
of the mean. This is part of the empirical rule, which states that 68% of data falls within one
standard deviation, 95% within two, and 99.7% within three standard deviations.
Question 3
,Which of the following measures can be used to find the central tendency of a dataset?
A) Mean
B) Median
C) Mode
D) All of the above
Correct Option: D
Rationale:
The central tendency of a dataset is represented by the mean, median, and mode. Each measure
provides different insights into the data: the mean is the average, the median is the middle value
when data is ordered, and the mode is the most frequently occurring value.
Question 4
What is the purpose of a confidence interval in statistics?
A) To estimate the range of a population parameter based on sample data.
B) To predict future outcomes based on past data.
C) To demonstrate the relationship between two variables.
D) To summarize the main features of a dataset.
Correct Option: A
Rationale:
A confidence interval provides a range of values that is estimated to contain a population
parameter, such as the population mean, with a certain level of confidence (e.g., 95%). It reflects
the uncertainty associated with sampling and gives a plausible range for the parameter based on
sample data.
Question 5
Which of the following statistical tests is appropriate for comparing the means of two
independent groups?
A) Paired t-test
B) ANOVA
C) Independent t-test
D) Chi-square test
Correct Option: C
, Rationale:
The independent t-test is used to compare the means of two independent groups to determine if
there is a statistically significant difference between them. The paired t-test is for related
samples, ANOVA is for comparing more than two groups, and the chi-square test is for
categorical data
Question 6
What is the purpose of regression analysis in statistics?
A) To summarize data
B) To describe the relationship between two variables
C) To test hypotheses
D) To analyze categorical data
Correct Option: B
Rationale:
Regression analysis is used to describe the relationship between a dependent variable and one or
more independent variables. It allows for predictions and insight into how changes in the
predictor variables affect the response variable.
Question 7
Which of the following describes a Type I error?
A) Rejecting a true null hypothesis
B) Failing to reject a false null hypothesis
C) Correctly accepting a true null hypothesis
D) Correctly rejecting a false null hypothesis
Correct Option: A
Rationale:
A Type I error occurs when the null hypothesis is true, but it is incorrectly rejected. This is also
referred to as a "false positive," and is associated with the significance level (α) set for a
hypothesis test.
Question 8
In a binomial distribution, what are the two parameters that define the distribution?
A) Mean and variance
B) Success probability and number of trials
StUdy GUide 2026 | objeCtive ASSeSSment (oA)
exAm prep, prACtiCe QUeStionS, Step-by-Step
StAtiStiCAl SolUtionS, verified AnSWerS & dAtA
AnAlySiS mAStery reSoUrCe
Exam: WGU C955 – Applied Probability & Statistics
Question 1
What is the meaning of a p-value in hypothesis testing?
A) The probability that the null hypothesis is true.
B) The probability of observing the sample data assuming the null hypothesis is true.
C) The level of significance set before conducting the test.
D) The probability of committing a Type II error.
Correct Option: B
Rationale:
The p-value measures the probability of observing the sample data (or something more extreme)
if the null hypothesis is true. It helps to determine whether to reject the null hypothesis. If the p-
value is less than the significance level (e.g., 0.05), it provides evidence against the null
hypothesis.
Question 2
In a normal distribution, what percentage of data falls within one standard deviation of the
mean?
A) 50%
B) 68%
C) 75%
D) 95%
Correct Option: B
Rationale:
In a normal distribution, approximately 68% of the data points fall within one standard deviation
of the mean. This is part of the empirical rule, which states that 68% of data falls within one
standard deviation, 95% within two, and 99.7% within three standard deviations.
Question 3
,Which of the following measures can be used to find the central tendency of a dataset?
A) Mean
B) Median
C) Mode
D) All of the above
Correct Option: D
Rationale:
The central tendency of a dataset is represented by the mean, median, and mode. Each measure
provides different insights into the data: the mean is the average, the median is the middle value
when data is ordered, and the mode is the most frequently occurring value.
Question 4
What is the purpose of a confidence interval in statistics?
A) To estimate the range of a population parameter based on sample data.
B) To predict future outcomes based on past data.
C) To demonstrate the relationship between two variables.
D) To summarize the main features of a dataset.
Correct Option: A
Rationale:
A confidence interval provides a range of values that is estimated to contain a population
parameter, such as the population mean, with a certain level of confidence (e.g., 95%). It reflects
the uncertainty associated with sampling and gives a plausible range for the parameter based on
sample data.
Question 5
Which of the following statistical tests is appropriate for comparing the means of two
independent groups?
A) Paired t-test
B) ANOVA
C) Independent t-test
D) Chi-square test
Correct Option: C
, Rationale:
The independent t-test is used to compare the means of two independent groups to determine if
there is a statistically significant difference between them. The paired t-test is for related
samples, ANOVA is for comparing more than two groups, and the chi-square test is for
categorical data
Question 6
What is the purpose of regression analysis in statistics?
A) To summarize data
B) To describe the relationship between two variables
C) To test hypotheses
D) To analyze categorical data
Correct Option: B
Rationale:
Regression analysis is used to describe the relationship between a dependent variable and one or
more independent variables. It allows for predictions and insight into how changes in the
predictor variables affect the response variable.
Question 7
Which of the following describes a Type I error?
A) Rejecting a true null hypothesis
B) Failing to reject a false null hypothesis
C) Correctly accepting a true null hypothesis
D) Correctly rejecting a false null hypothesis
Correct Option: A
Rationale:
A Type I error occurs when the null hypothesis is true, but it is incorrectly rejected. This is also
referred to as a "false positive," and is associated with the significance level (α) set for a
hypothesis test.
Question 8
In a binomial distribution, what are the two parameters that define the distribution?
A) Mean and variance
B) Success probability and number of trials
