Algebra 2
February 19, 2009
1.
2.
A set of values has a mean of 300 and a
standard deviation of 60. What value has a
z-score of -1.2?
In a survey of 683 car owners selected at
random, 235 reported paying cash for their
first car.
◦ A) Find the sample proportion
◦ B) Find the margin of error
◦ C) Find an interval likely to contain the true
population proportion

Features of a binomial experiment:
1.
Repeated trials
2.
Only two possible outcomes per trial
3.
Probability of success is the same in each
trial

Example 1: Suppose that you guess the answers to
three questions of a multiple choice test. Each
question has five choices, with one correct choice.
1. What
is a trial for this experiment? How many trials
are there?
1. What
is a success? What is the probability of
success on each trial?

1.
2.
Example 2: Suppose you and a friend flip a coin
five times to find out who gets to play an arcade
game first. The person who gets three out of five
flips wins. Your winning side is heads.
What is a trial for this experiment? How many
trials are there?
What is a success? What is the probability for
success on each trial?

Binomial Probability Formula:
n = number of trials
r = number of successes
p = probability of success
q = probability of failure

Example 3: Alicia walks to school with her
friend MacKenzie. MacKenzie is on time 80%
of the time. What is the probability that
MacKenzie will be on time 5 days in a row?

Example 4: A fast food restaurant is attaching
prize cards to every one of its soft drink cups.
The restaurant awards free drinks as prizes
on three out of four cards. Suppose you have
three cards. Find the probability that exactly
one of these cards will reveal a free soft drink
as its prize.


To find the full probability distribution for a
binomial experiment, expand the binomial
Example 5: Suppose you guess on four
questions on a multiple choice test. Each
question has 5 choices. The probability of
guessing correctly is 0.2

Example 6: A scientist hopes to launch a
weather balloon on one of the next three
mornings. For each morning, there is a 40%
chance of suitable weather. What is the
probability that there will be at least one
morning with suitable weather?
Normal Distributions


Every normal curve has a symmetric bell
shape (“the bell curve”).
The jaw widths of a population of great white
sharks are normally distributed about a mean
of 15.7 inches. The standard deviation is 2.8
inches. Sketch a normal curve showing the
jaw widths at one, two, and three standard
deviations from the mean.
TOOK OUT OF LESSON!!!

In a survey, the responses to the question
“How much time do you spend at meals in
one week?” were normally distributed. The
mean was 13 hours. The standard deviation
was 3 hours.
◦ A) What values are one standard deviation from the
mean?
TOOK OUT OF LESSON!!!

In a survey, the responses to the questions
“How much time do you spend in the shower
daily?” were normally distributed. The mean
was 15 minutes; the standard deviation was 2
minutes.
◦ A) What values are one standard deviation from the
mean?

In a Psychology class at CSU with 174
students, the final exam scores have a mean
of 68.5 and a standard deviation of 7.3. The
grade pattern of the exams follows a normal
curve.
◦ About how many students receive grades from one
to two standard deviations above the mean?
◦ About how many students receive grades of 61 or
below?
 Page
689 #8-12, 25a
 Page
695 #1, 4, 5, 11-15