WGU C955 Probability and Statistics Objective Assessment Exam Questions and Answers () (Verified by Expert)2024-2025
Wgu c955 probability and statistics objective assessment exam questions
Wgu c955 probability and statistics objective assessment exam answers
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Discrete data Has distinct values, can be counted, had unconnected points (think dots)
Continuous data Has values within a range, measured not counted, does not have gaps between data points (data is connected lines or curves).
Example of discrete data Days of the week
Expressions A group of symbols such as numbers and operators that has mathematical validity
Commutative The order in which the numbers appear in the sum can be reversed
Identity property Adding 0 to any number does not change the original number
Additive inverse Values that are equally far from 0 on the number line.
Negative When multiplying a positive number by a negative number the result is always
Positive Multiplying a negative number by a negative number results in a positive
Factors Integers that evenly divide the initial integer
Prime number Positive integer with exactly two positive factors consisting of 1 and itself
Composite number Has at least one positive factor other than one and itself
Factorization Process of breaking up a composite number into its prime factors
fundamental theorem of arithmetic Any integer greater than one is either Prime or the product of Prime numbers
Principal square root Positive square root of a number
Radican Number under radical sign √16=4
Open Circle Represents less than or greatest than on the number line
Perfect square Product of any integer with itself yields a perfect square.
Whole numbers positive numbers with a whole value
Integers Numbers with no fractions or decimal value but can be positive or negative
Rational numbers Numbers that can be expressed as a fraction or decimal values that have that end or repeat forever. Includes all integers since all integers can be expressed as fractions.
Real numbers Everything that can be included in a number line including pi.
Fractions Express numbers which are part of a whole
Numerator Number written before the slash or above the fraction bar
Proper fraction Numerator is less than denominator and the value of the fraction is less than one
Improper fraction Numerator is greater than denominator and therefore is greater than one except with negative fractions
Mixed numbers A whole number and proper fraction. A negative sign in front applies to both parts of the mixed number.
Multiples Integers created by multiplying one number times another number
Fractions Express numbers which are part of a whole
Numerator Number written before the slash or above the fraction bar
Proper fraction Numerator is less than denominator and the value of the fraction is less than one
Improper fraction Numerator is greater than denominator and therefore is greater than one except with negative fractions
Mixed numbers A whole number and proper fraction. A negative sign in front applies to both parts of the mixed number.
Multiples Integers created by multiplying one number times another number
Reciprocal The number which of multiplied by divisor gives you one (like the fraction flipped over)
Terminal decimal Has digits that end
Ratio Comparison of two numbers
Rate A ratio that compares two quantities having different units of measure
Proportion True statement in which two ratios are equal to each other. Two days are proportional of they are equivalent.
Conditional proportion One part of a proportion is a variable or unknown quantity
Celsius to Fahrenheit Celsius x 9/5 + 32
Fahrenheit to Celsius (Fahrenheit – 32) x 5/9
Constant Number with a fixed value. All real numbers are constants
Elementary operations Addition, subtraction, multiplication, division
Base The number an exponent is written next to
Variable Symbol that represents our holds the place of a numerical value
Coefficient A number by which a variable is being multiplied. Coefficients are written in front of variables. 16x, 16 is coefficient. If there is no number you assume an invisible1.
Term Can be a single constant, a single, or a number of constants and variables multiplied together.
Algebraic expression String of terms connected by division, addition, and subtraction.
How to write an algebraic expression Constants at end. Write terms with the largest exponents first. Always write in descending order of exponent value with constants at the end.
Inverse operation Operations that undo each other. Subtraction is inverse of addition. Division is inverse of multiplication.
Like terms Have the same variable with the same exponent
Degree of an expression Refers to largest exponent in an expression
Linear Has degree of 1
Quadratic Has degree of 2
Cubic Has degree of 3
Constant Has degree of 0
Distributive property Principle used to multiply a single term by multiple terms. If there are parenthesis around multiple terms which are in turn multiplied by a single term, we can use this property.
TermText TermText 2
Boxplot an image that has min, Q1, median, Q3, max
Histogram A graphical representation — bars, measuring the frequency within each interval
Skewed right Not a symmetric distribution, the tail is on the right, i.e. extra stuff on the right
Measures of center Median, the mean (and mode)
Measures of spread Range, IQR & standard deviation
Standard Deviation Rule 68% of the data are within 1 standard deviation, 95% are within 2, 99.7 are within 3 standard deviations from the mean.
For skewed data, use these for center and spread In this situation, we use median (for center) & IQR (for spread)
Explanatory variable “In a study, what we think is the “”cause”””
Response variable “In a study, what we think is the “”effect”””
Scatter plot A graphical representation of Q -> Q
Two way table A graphical representation of C -> C
Side-by side box A graphical representation of C -> Q
Linear relationship “””shaped like a line”””
Correlation coefficient, r Between -1 and 1; measures how close the points are to the line and if the trend is uphill (positive) or downhill (negative).
r = -0.2, for example This is an example of a correlation coefficient that represents a weak negative correlation.
r = 0.9, for example This is an example of a correlation coefficient that represents a strong positive correlation.
Linear regression line A line that fits the data as close as possible, used to make predictions
Interpolation Making predictions the range of your data. This is usually accurate.
Extrapolation Making predictions of the range of your data. This is generally a bad idea.
Simpson’s Paradox When split up, each data set can have a pattern which goes away when all the data is combined.
Only way to prove causation Experiments, because they account for lurking variables
Observational study A type of study where we measure or survey members of a sample without trying to affect them. Cannot prove causation.
Experimental study A study where you split subjects up randomly and impose a change on one group to study the effect; can prove causation
Prospective study Is a study that’s done over time to find results / A study watching for outcomes during the study period
Retrospective study A study that looks backwards to assess outcomes and possible causes after the fact
Control group randomly assign people or things to groups. One group receives a treatment and the other group does not. This is the group that does not receive treatment
Placebo A substance or procedure that has no effect used for comparison to the real substance or procedure
Placebo effect A beneficial effect produced by the belief of the patient/subject, not by the intervention itself.
Experimenter effect When the persons running an experiment affects its results by influencing the subjects inadvertently
Open question A question that gives the responder freedom to answer in many different ways — harder to analyze with statistics.
Closed question A question with limited choices, e.g. multiple choice or yes/no. Easier to analyze statistically.
Unbalanced response Giving more options that are negative than positive options (or vice versa) which biases the responses towards the more common option
Matched pairs Grouping two similar subjects and giving different treatments/procedures to each in order to compare the differences. For example, having one twin take a medication while the other twin does not.
Blind experimental study When information of a study isn’t revealed to the participants
Double Blind Study When information of study is hidden from the researcher and the participant.
Population The entire group you are trying to describe or understand.
Sampling frame List of group from which you choose your sample.
Sample The group that is actually picked to be included in a study
Simple random sample making a selection by following a random pattern and selecting without replacement. Unbiased.
Systematic sample Sample is selected by listing the sampling frame, then making a selection by following a simple pattern (eg. Every 20th name). Unbiased.
Voluntary sample Members of the sample may choose not to respond. Similar to Non Response.
Convenience sample Participants are easy for researcher to access. Tends to increase bias.
Cluster sample Sample frame is divided into groups, we select a few groups, then selecting ALL of the members of those groups.
Stratified sample Sample frame is divided into groups. Then we choose a random sample (usually the same size) from within EVERY group.
Multi-stage sample Multiple rounds of randomness and grouping. For example: randomly selecting a few groups, then choosing a small random sample just those selected groups. Often a combination of Cluster and Stratified Sampling.
The formula for all simple probabilities (number of possible outcomes for the specific event) / (total number of possible outcomes)
For independent events, P(A and B) = ? P(A)P(B) For independent events, P(A|B) = ? P(A) [this is the right side of which probability formula?] P(A|B) = ? P(A and B) ÷ P(B) P(A or B) = ? P(A) + P(B) – P(A and B) In general, P(A and B) = ? P(A)P(B|A)