Units 1&2
What is the mean of the following numbers? 10, 39, 71, 39, 76, 38, 25
42.5
How do you know if a problem is binomial or geometric?
binomial has a fixed number of trials before the experiment begins and X counts the number of successes obtained in that fixed number.
Geometric: has a fixed number of successes and counts the number of trials needed to obtain that first success.
A committee of 5 people is to be formed randomly from a group of 10 women and 6 men. Find the probability that the committee has 5 women.
0.288461
if tail alpha is .05 and the df= 20
is the graph left-tailed, right-tailed, or two-tailed
left-tailed
A poker-dealing machine is supposed to deal cards at random, as if from an infinite deck. In a test, you counted 1600 cards, and observed the following: Spades 404 Hearts 420 Diamonds 400 Clubs 376 Could it be that the suits are equally likely? Or are these discrepancies too much to be random
it is randomly picked
The teacher of a class of third graders records the eye color of each student. Is this measurement nominal, ordinal, ratio, or interval?
SOLUTION: This is the nominal level of measurement. Eye color is not a number, and so the lowest level of measurement is used.
Classify each random variable as either discrete or continuous.
1. discrete
2. continuous
3. continuous
When working with the sampling distribution of a sample statistic, which of the choices would decrease the margin of error?
a. Increase the sample size.
b. Decrease the sample size.
c. Increase the standard error.
a. Increase the sample size.
if the tail alpha is 0.05 and the df=14
is the graph left-tailed, right-tailed, or two-tailed?
right tailed.
When working with the sampling distribution of a sample statistic, which of the choices would decrease the margin of error?
a. Increase the sample size.
b. Decrease the sample size.
c. Increase the standard error.
a. Increase the sample size.
Identify the population and the sample-
A survey of 1353 American households found that 18% of the households own a computer.
population: all American households'
sample: collection of 1353 American households surveyed
Classify each random variable as either discrete or continuous.
1. discrete
2. continuous
3. discrete
We want to construct a 95% confidence interval for p with a margin of error equal to 4%.
Because there is no estimate of the proportion given, we use p~=0.50 for a conservative estimate.
n=601
alpha tail= 0.05
df=20
what is the P-value?
-1.752
if tail alpha is .05 and the df= 20
is the graph left-tailed, right-tailed, or two-tailed
left-tailed
Scores on a history test have average of 80 with standard deviation of 6. What is the z-score for a student who earned a 75 on the test?
z score= -0.833.
The probability which is based on the observations of an experiment is called?
Experimental Probability
Given the population of elements: {22, 24, 26}.
Calculate the variance of the population.
u=24
o2=8/3
In a sample of 1000 home buyers, you find that 457 home buyers found their real estate agent through a friend. At α=0.08, can you reject the claim that 50% of home buyers find their real estate agent through a friend?
Ho: p = 0.50; Ha: p ≠ 0.50.
You grow 20 crystals from a solution and measure the length of each crystal in millimeters. Here is your data:
9, 2, 5, 4, 12, 7, 8, 11, 9, 3, 7, 4, 12, 5, 4, 10, 9, 6, 9, 4
3.061
You grow 20 crystals from a solution and measure the length of each crystal in millimeters. Here is your data:
9, 2, 5, 4, 12, 7, 8, 11, 9, 3, 7, 4, 12, 5, 4, 10, 9, 6, 9, 4
3.061
If the events have the same theoretical probability of happening, then they are called?
a. Mutually exclusive events
b. Mutually exhaustive events
c. Equally likely events
d. Impossible events
c. Equally likely events
Which choice is the margin of error, with a confidence level of 95%, for estimating the proportion of green mini M&Ms in a container, if 21 green mini M&Ms were drawn from the container in a random sample of 100 M&Ms?
a. 0.041
b. 0.081
c. 0.210
d. 0.105
b. 0.081
Mike gave the SAT math test to a simple random sample of 500 seniors from Illinois. These students had a mean score of 461 ( x ). Is this good evidence that the mean for all Illinois seniors is > 450. σ = 10
does this use a sample z test, sample t test, proportion z test.
sample z test
alpha tail= 0.05
df=20
what is the P-value?
-1.752