Exam (elaborations)
Statistics (Stat 2023) Exam Quiz Module 4
- Course
- Elementary Statistics
- Institution
- St. Petersburg College
Statistics (Stat 2023) Exam Quiz Module 4
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St Petersburg College FloridaStatistics (Stat 2023) Exam Quiz
Module 4
Course Title and Number: Statistics (Stat 2023) Quiz module 4
Exam Title: [Insert Exam Title]
Exam Date: [Insert Exam Date]
Instructor: [Insert Instructor’s Name]
Student Name: [Insert Student’s Name]
Student ID: [Insert Student ID]
Examination
180 minutes
Instructions:
1. Read each question carefully.
2. Answer all questions.
3. Use the provided answer sheet to mark your responses.
4. Ensure all answers are final before submitting the exam.
Good Luck!
, Statistics (Stat 2023) Exam Quiz
Module 4
What term refers to a frequency distribution that follows a bell-
shaped, symmetrical, and unimodal curve? - Answer>>
normal distribution
In a normal distribution, the mean is located where? -
Answer>> in the middle of the curve
T/F For a normal curve, the median, mean, and mode are
typically equal
T/F The area below the curve is 120%. - Answer>> True
False. 100% or 1.00
T/F The greater the standard deviation, the less spread out the
normal curve. - Answer>> FALSE
The greater the standard deviation, the more spread out the
normal curve. The smaller the standard deviation, the narrower
the normal curve.
A normal distribution can be defined by its ___ and ______. -
Answer>> mean and standard deviation
the ___-___-___ rule
con? - Answer>> 68-95-99.7
However, the rule only works when values are exactly 1, 2, or 3
standard deviations away from the mean. In order to apply the
concept of proportions to other standard deviation values, such
as σ = ± 1.4 or σ = ± 2.3, scores or values in the dataset must
be standardized.
,an exact value that is observed - Answer>> raw score
indicates exactly how many standard deviations a raw score is
above or below the mean. - Answer>> standard score
describes the exact location of a raw score within the whole
distribution when compared to the mean. It converts each raw
score X into a signed, numerical value.
also known as standard scores - Answer>> z-score
What does a +z-score mean?
what does a -z-score mean? - Answer>> the value from the
dataset lies above the mean
the value from the dataset lies below the mean
Coverting raw scores to z-scores - Answer>> z= (raw score-
mean)/ standard deviation
Converting z-scores to raw scores - Answer>> raw score=
mean + z * standard deviation
Comparing Values using z-Scores and Raw Scores
When comparing z-scores from the same population or sample,
it may be more meaningful to convert the z-score back to a raw
score. For example, compare the performances of the following
students on the physiology exam (μ = 87 , σ = 4 ) given the -
scores listed below for Josef, Marco, and Brooklyn.
Josef: z=-1.75
Marco: z=-2.50
Brooklyn: z=1.25 - Answer>> Convert each z-score to a raw
score. Then compare the raw scores.
Josef: X=87 - 1.75(4) = 80
Marco: X= 87 - 2.50(4) = 77
, Brooklyn: X= 87 + 1.25(4) = 92
z-Scores for Sample Means from a Population - Answer>>
(sample mean-population mean)/ population mean/ sqrt(sample
size)
Consider the example of the exam scores from Figure 4.3 ( μ =
75 , σ = 5 ). Suppose the teacher would like to know the
proportion of scores on the exam that are below 65. -
Answer>> 1. transform raw score to a z-score
2 use normal table to find the p-value for z score
The proportion of scores below the z= -2.00 is 0.02275 or
2.275%. Therefore, a test score below 65 is unusual since less
than 2.275% of the scores fall below it.
a range of values that is likely to contain the true population
mean. - Answer>> confidence interval
What states that the distribution containing all sample means
will approach the population mean. This implies that the
population mean will be close to the sample mean. -
Answer>> The Central Limit Theorem
95% confidence interval - Answer>> he 95% confidence
interval, for example, means that 95% of the experiments with
the given treatment will contain the true population mean.
Consequently, 5% (or 1 in 20) of the experiments will not
contain the true population mean. A 95% confidence interval
implies that the researcher is 95% confident that the population
mean lies in the interval that is centered around the sample
mean.
margin of error - Answer>> z crit *(population standard
deviation/ sqrt (sample size)
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