Download Revision of Preparing For The AP Statistics Exam

Revision of Preparing For The AP Statistics Exam
Chapter 5
Some more changes to earlier chapters:
Ch
Sec
Pg
Prob
Change
2
2
15
MC4
Drop answer (E)
Answer Change
Add to stem: If all of theses choices can be
generated, then select answer (E).
2
5
30
MC9
Drop answer (E)
Add to stem: If (A) through (D) are true, then select
answer (E).
3.
3
46
MC1
Drop answer (E)
Add to stem: If each statement is a correct
interpretation of r = -0.30, then select answer (E).
3
3
46
MC3
Drop answer (E)
Add to stem: If each statement is true about a
correlation coefficient, then select answer (E).
3
4
52
MC2
Drop answer (E)
Add to stem: If all of (A) through (D) are reasonable
conclusions, then select answer (E).
3
6
65
MC2
Drop answer (E)
Add to stem: If all of (A) through (D) are reasonable
techniques, then select answer (E).
3
Ch
70
MC2
Assess
Drop answer (E)
Add to stem: If all of (A) through (D) true, then
select answer (E).
3
Ch
70
Assess
MC6
Change answer (E)
Two different sets of data can have the same set of
z-scores.
Still seems a little weird to me to drop E from the list of options…
Chapter 5
Sec
Pg
98
Prob
Change
Very end of page, could delete “percent” option or discuss
it separately (especially since next line talks about being
between 0 and 1)?
99
Around example 2 I noticed that the book isn’t too
Answer Change
consistent on P(A) vs. P(A) (italicizing of ()s). Not a big
deal.
2nd result of basic probability rules, probably better to talk
100
about the events being complements rather than the
probabilities?
100
Ex 4
Really want a sample proportion that is that far from .5?
 Could also use  symbols in here?
1
How about “is greater than some fixed number a.”?
101
Para 1
102
MC3
Change answer (E) to S < 12. This is MC2?
103
MC4
The font in choice I is different. For choice II, how about
“it has been determined that the probability is .12 that an
inhabitant…”
103
MC5
Could include YXXZ as a distractor? I couldn’t justify any
others but (A)?
103
FR3b
Answer is wrong? Should be neither? (see later
calculation of probability) Also, could say “if repeatedly
roll pairs of dice”. I was also a little confused in (d). Can’t
success – “accident in 50 miles” (you have fixed the
distance), could say the probability depends on which 50
mile stretch type thing?
104
Ex 1
Maybe in b. some thing like “the probability of obtaining
an ace of the 2nd draw is again 4/52, regardless of the
outcome of the first draw?
105
Cond
Before the last formula, do you mean to refer to the
prob
calculation of condition probability rather than the
Multiplication rule?
2
108
MC2
Drop both questions. See replacements below.
MC3
2
108
MC6
Change answer (E) to 0.97
110
Ex 2
Maybe say “How many ways can you select and arrange
4 out of 7…”
110
Tech
Is MATH PRB true across different brands? Later you
note
refer to TI 83, need to here?
Are you purposely not using P(S=3) type notation here?
Do you want to justify why the multiplier in the binomial is
a combination rather than a permutation more?
3
117
TEXT
Last line in Example 5 should read
(30/36)(30/36)(6/36)=25/216
4
118
MC4
Drop answer (E)
Add to stem: If all are shared by binomial and geometric
probability situations, then select answer (E).
118
Mc5
Want to add strictly to A?
119
FR5
Seems out of place when you told them to assume it was
true in 3-8
119
FR8
Reword this one? For example: A teacher constructs his
exams so that 70% of the time all students will pass the
exam… (I got lost of the all of students vs. of the time)
5
119
Intro
Change “treat” to “consider” in first paragraph?
I wonder if these should not be called “probability plots”
since that has a different technical meaning. Maybe
probability function? Some books call them probability
histograms…
120
Tech
I don’t have a calculator here is “seq(x,x,0,4,1)” correct? It
note
confused me
I’m also torn on calling this “standard error” instead of
121
standard deviation
122
Ex 3
Want to calculate the standard deviation for them?
122
MC2-
Should it say “of the legitimate distributions”? Could
3
change explanation in 3 from “smallest range” to
“probabilities are concentrated in a smaller range of
values”?
5
122
MC4
Should stem say something about “all” distributions?
Change answer (E); The graph of the distribution is
skewed left.
MC 6
A little awkward to go back and forth between probability
distributions and data in this way
6
124
OE 1
Same question about “probability plots”
OE 5
Change “determine” to ‘decide”?
Para 1
After cdf how about “and therefore the probability, under
the curve from negative infinity to the value of interest of
the continuous random variable?
125
Ex 1
Want to tell them to label the variable on the horizontal
axis and do so in the solution?
126
Calc
1. How about The first two parameters must be included.
The last two are optional and if not included the calculator
will use…”
Also, is the TI really “representing infinity” or are we just
using a very large and a very small number in its place?
127
Ex 4
At very end of box say something “is close to .80”?
128
MC1
Why is D wrong and could say “which is a true statement
about the 80th percentile” unless D is wrong because it is
not a definition?
6
128
MC3
Answer on page 344: add the underlined words, please:
Using z-scores to calculate percentages of data should…
Could talk about probabilities instead of percentages of
data?
129
Para 2
How about “we are finding a discrete probability using a
continuous distribution.”
132-3
The approximation comparisons are a little strange, some
of the ones you say aren’t so good have a smaller
absolute difference that the ones you say are good?
133
Notes
Delete 1 or reword at least about the sum of the y
coordinates?
*Do you ever want to mention anywhere that P(X=x) must
be zero for a continuous rv? Also could reinforce that
with continuous P(X
133
MC1
 x) = P(X<x)?
Reword (D): the binomial distribution is not so severely
skewed that..”
136
Ex 4
Isn’t this a good example of the difference between 3X
and X1+X2+X3? I would change SD calculation and
really reinforce that here.
7
138
MC1
133?
7
138
Change answer 1: Sample size must be large enough to
reduce non-response bias in the data.
MC2
Change stem to correct.
MC2
In stem, reword as “A new game with two dice is being
133?
138
played on some…”?
8
139
FR3
Change beginning of problem:
The American Mathematics Exam (AMC-12)…. has 150
possible points while the American Invitational Exam
(AIME) has only 15 possible points. In order to invited to
take the AIME, a students must score at least 100 on the
AMC-12 exam…..
9
139
Intro
Are 1. and 2. for discrete or for both? If both, maybe say
the probability of the sample space needs to be one?
The term probability density function is being used with
discrete variables. Let’s not use “density” here. Could
use “mass” as in other locations…
140
Ex
The domain of B(10,.3)
141
Pre
Want to say “or N(, )” here?
Ex4
142
Chi
142
Want to label the two curves?
Bottom 2 paragraphs seem a little mis-ordered. Could
insert last paragraph before “If this parameter is
deleted…”
9
143
MC2
Drop answer (E)
Add to stem: If all of (A) through (D) define legitimate
uniform probability density functions, then select answer
(E).
143
MC4
Maybe more symmetric instead of (or in addition to)
flatter?
144
Ex 1
I got a little confused in sum(randInt) explanation. Maybe
something like “Therefore, the statement
sum(randInt(0,9,10)  3) totals the number of 1’s in the list
of Boolean outcomes”?
145
Before
b
I would just say “So the mean of these trials,
96/23=4.1739, estimates the expected number of boxes
we would have to buy until a picture of Babe Ruth
appears.” (I don’t like the “a minimum of 5 boxes…”
145
OE1
Really want same probability as in the preceding
example?
146
4
In stem, was 15% supposed to be changed to 20% or
change solution?
d. to estimate the expected number of events that will
occur
148
FR5
Don’t use density in the first sentence, maybe “Probability
functions generate… between the density functions for
continuous variables and mass functions for discrete
variables.”
341
MC5
Could change “percent” to “proportion”
342
MC7
Change .06 to .006
347
9
347
IT2
Were some “not”s still supposed to be deleted?
Did graph still need to be changed?
Replacement for MC2 and MC3 in section 5.2, page 108.
Use the following to answer questions 2 and 3.
The results of a survey of 50 high school students’ choice of favorite pet is summarized in the table
below:
Dog
Cat
Other
Girls
15
10
5
Boys
12
3
5
What is the probability that one of the survey students, selected at random will be
2. A girl whose favorite pet is a cat?
(A) 10/50
(B) 10/13
(C) 10/30
(D) 13/50
(E) 30/50
(D) 13/50
(E) 30/50
3. A girl given that cat was the selected favorite pet?
(A) 10/50
answers A and B?
(B) 10/13
(C) 10/30