#### Transcript Review Angles & Triangles

```AP Stat Review
Descriptive
Statistics
Experimental
Design
Probability
Inferential
Statistics
Conditions
Grab Bag
100 points
If the mean of a distribution is greater than
its median, what is most likely the shape of
the distribution?
Skewed right
200 points
If the range of a set of data is 36, what
is a reasonable estimate of the standard
deviation?
6
300 points
If the test scores of a class of 30 students
have a mean of 75.6 and the test scores of
another class of 24 students have a mean of
68.4, then the mean of the combined group
is…
72.4
400 points
Joey scored a 720 on the math portion of the
SAT and Luke scored a 34 on the math
portion of the ACT. Scores for each test are
Normally distributed. The SAT has a mean
of 580 and a standard deviation of 100, while
the ACT has a mean of 26 with a standard
deviation of 5. Who had the better relative
performance?
Luke
500 points
• For a particular bivariate data set, r2 is
found to be 0.64. Interpret this value.
64% of the variation in y can be
accounted for by least squares
regression of y on x.
100 points
When do we say that the design of a study is
biased?
When certain outcomes are
systematically favored.
200 points
What is the difference between an
observational study and an experiment?
In an experiment, a treatment is applied.
300 points
A research team wishes to compare
performance in AP Statistics based on
whether the students were taught using
The final grades in AP Statistics for 500
students were collected. What is the
population of interest?
All students taking AP Statistics
400 points
Name four components for a valid
controlled experiment.
Control, comparison, replication, and
randomization
500 points
What is the purpose of a control group in an
experiment?
To control the effect of lurking variables and
to reduce bias
100 points
A company claims that the number of defective
items manufactured during each run of making 100
of their products is independent of the number
from other runs and that the proportion of
defectives is no more than 4%. Assume that the
proportion of defectives for each run is .04. What is
the probability that there will be no defectives on the
next run?
0.017
200 points
The number of sweatshirts a vendor sells daily
has the following probability distribution:
X
0
1
2
3
4
5
P(X)
0.3
0.2
0.3
0.1
0.08
0.02
If each sweatshirt sells for \$25, what is the
expected daily total dollar amount taken in by
the vendor from the sale of sweatshirts?
\$38
300 points
In a certain game, a fair die is rolled and a player
gains 20 points if the die shows a “6.” If the die
does not show a “6,” the player loses 3 points. If
the die were to be rolled 100 times, what would be
the expected total gain or loss for the player?
400 points
All bags entering a research facility are screened.
Ninety-seven percent of the bags that contain
forbidden material trigger an alarm. Fifteen
percent of the bags that do not contain forbidden
material also trigger the alarm. If 1 out of every
1,000 bags entering the building contains
forbidden material, what is the probability that a
bag that triggers the alarm will actually contain
forbidden material?
0.00643
500 points
A student is taking a 5 question multiple choice test.
Each question has 4 choices of answers. If a
student randomly answers the questions find the
probability that the student answers at least 4
questions correctly.
0.015625
100 points
A P-value of a test of significance is the probability
that…
A sample of this size will
produce a statistic this or
more extreme if the null
hypothesis is true.
200 points
Correct this statement: if the P-value of a test is
greater than α, we accept the null hypothesis.
We fail to reject the hull hypothesis
300 points
What is a type I error?
We reject the null hypothesis
when we should not have.
400 points
Name two way we can reduce the width of a
confidence interval?
Increase sample size; reduce the
confidence level
500 points
A local news station reports that the 97%
confidence interval for a candidate’s support
was (43%, 48%). What does the phrase 97%
confidence mean?
If we repeated this procedure many times, 97% of the
resulting CI’s would contain the true population proportion.
100 points
List the conditions for a one-sample z-test.
SRS; Normality;
Independence; σ is known.
200 points
Name the conditions for a one-proportion z-test.
SRS;
np ≥ 10 and n(1 – p) ≥ 10;
population > 10*sample
300 points
Name the conditions for Chi-square GOF test.
SRS;
All expected counts ≥ 1; No more than 20%
of expected counts < 5
400 points
How do we show Normality for a t-test?
Stated; n > 30 (CLT); n > 15 with no clear
outliers (CLT); n < 15 with no skewness or
outliers (CLT)
500 points
What do we say if a condition is not met?
Continue with the test, but we have
concerns over the results.
100 points
What is z* for a 95% confidence
interval?
1.96
200 points
What is t* for a 90% confidence interval for a
sample size of 30?
1.7011
300 points
A large company is considering opening a franchise in St. Louis and
wants to estimate the mean household income for the area using a
simple random sample of households. Based on information from a
pilot study, the company assumes that the standard deviation of
household incomes is σ = \$7,200. Of the following, which is the least
number of households that should be surveyed to obtain an estimate
that is within \$200 of the true mean household income with 95%
confidence?