Using Formulas
Random Variables
From a Table
Binomial and Geometric
100
P(A) = .2, P(B) = .75, P(A and B) = .11
Find P(A or B)
P(A or B) = .84
0.2 +0.75-0.11
100
If events A and B are independent, P(A | B) =
P(A)
100
Find the probability that a randomly chosen student is a freshman.
0.2261
100
What is a key word that tells you it's a geometric problem?
until
200
P(A) = .33, P(B) = .4,
Find P(A or B) if events A and B are mutually exclusive
.73
200
Let X be a random variable where X = the number of heads flipped in 4 coin flips. Find P(X = 2)
6/16
200
Find the probability that a randomly chosen freshman plays video games.
0.6667
200
Tim makes 80% of his free throws. In a game, he takes 14 free throw attempts. Find the mean and standard deviation of the distribution
mean = (.8)(14)
mean=14*0.8=11.2
SD=sqrt(14*0.80*0.20)=1.496
300
P(A) = .5, P(B) = .75
Find P(A and B) if the events are independent.
.375
(just multiply them)
300
Find the expected value for the game:
Roll 2 dice,
Sum < 4, win $10
Sum > 10, win $20
10(3/36) + 20(3/36)
30/36 + 60/36 = 90/36 = 2.5
300
Find the probability that a randomly chosen video game player is a freshman.
0.2609
300
You take a 30 question multiple choice test (choices A-D for each question), and unfortunately know nothing on it. If you were to guess on every question, what is the probability that you get 5 questions correct?
binomialpdf(30,.25,5)
.1047
400
P(A) = .20, P(B) = .39
Find P(A or B) if events A and B are independent
.512
0.20 +0.39-0.20*0.39
400
Let X = height of students, in inches, at an elementary school. X is a Normally distributed variable.
If the mean and standard deviation are 52 and 4.7, respectively, find the probability that a randomly selected student would be taller than 60 inches.
.0444
400
Are playing video games and being a freshman mutually exclusive? Explain.
no
400
A wide receiver has a catch rate of 40%. What is the probability that his first catch will be before his 3rd target?
geometriccdf(.4,2)
500
If two events are mutually exclusive, what else can you determine?
A) They are independent
B) They are not independent
C) One cannot determine whether or not they are independent
B
500
What is the mean and standard deviation of X?
mean = 1.45
SD = 1.268
500
Are playing video games and being a freshman independent? Explain.
no
500
The AP Stats Midterm Exam has 100 multiple choice questions (A-E choices). Wanda hasn't paid attention all year and guesses on every single one of them. If X is the # of questions correct, find P(X>22)
0.3459