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Quiz 4 Review Flashcards | StudBud
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Quiz 4 Review
Quiz 4 Review
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Questions
20
Answers
1
what should be the sample size when estimating means (when its not bell shaped)
does not matter
n≥30
3
n>10
2
Use the empirical rule to estimate the probability of a lion living longer than 7.2 years.
99.70%
97.5%
67%
95%
3
How large does a sample size need to be to apply the Central Limit theorem?
10
15
30 or greater
it depends
4
What is the standard deviation of the following normal distribution?
13
3
not enough info
16
5
As sample size increases, what happens to the width of the interval?
it becomes infinite
decreases
stays the same
increases
6
What is the area to the right of a value with a z-score=1.75? (assume normality)
0.0401
130
121.24
.9599
7
When estimating proportions what should be the sample size for both category of interest/not of interest?
5
n<10
n≥10
n>30
8
What does this symbol represent?
Population mean
Mean of the standard deviations
Mean for a sampling distribution
sample mean
9
Increasing your sample size has what effect?
nothing
It increases the margin of error in your results
it decreases the power of your statistical tests.
reduces variability
10
As standard deviation increases, what happens to the overall shape of your distribution?
doesn't change
no change
gets flatter
gets narrow
11
When U (mu) is not known we use what as an estimate?
X
X-bar
p-hat
Y bar
12
What does this image represent?
margin error (for proportions)
confidence interval
standard deviation
margin of error (for means)
13
If a value has a Z-score of -2, where does it fall in relation to the mean?
2 standard deviations below the mean
1 standard deviation below the mean.
At the mean
2 standard deviations above the mean.
14
Sam sold 34 bags of popcorn. If the mean number of bags sold was 38 with a stand dev of 2.5, find Sam's z score
34
1.6
idk
-1.6
15
What is the area to the left of a value with a z-score =1.75? (assume normality)
.9599
.9591
.9495
0.0401
16
As the confidence level increases, what happens to the width of the interval?
it does not change
width increases
width decreases
not enough info
17
How many did he download?
28
22
20
3
18
What is the main goal of inferential statistics?
To summarize and describe the features of a data set
it doesn't do anything
Collecting information from a sample to make estimates about the population
To collect data from a sample
19
Which best describes the standard deviation?
not sure
how spread out a group of numbers is from the mean
the middle value of a data set when it is ordered from least to greatest
the difference between the highest and lowest values in a data set
20
Normal Distribution is symmetric around it's ______
covarience
mode
mean
standard deviation
