A simple random sample of 100 observations was taken from a large population. The sample mean is 80 and the population standard deviation is 12. The standard error of the mean is
1.20
A histogram is
a graphical presentation of a frequency or relative frequency distribution
Smaller values of the standard deviation result in a normal curve that is
narrower and more peaked
In hypothesis testing, the tentative assumption about the population parameter is
the null hypothesis is true
If P(A) = 0.50, P(B) = 0.60, and P(A?B) = 0.30, then P(A?B) =
.80
(Round your answer to three decimal places.) In a one-tail (upper tail) hypothesis test situation, the test statistic is determined to be t = 2.692. The sample size is 45. The p-value for this test is
0.0050
An insurance company selected samples of clients under 18 years of age and over 18 and recorded the number of accidents they had in the previous year. The results are shown below.
Under Age of 18 Over Age of 18
n1 = 500 n2 = 600
Number of accidents = 180
pu is not equal to po
A sampling method in which you randomly select one of the first k elements and then select every kth element thereafter
Systematic sampling
A sampling method is which the population is first divided into groups and a simple random sample of groups is taken.
Cluster sampling
A sampling method in which the population is first divided into groups and a simple random sample is taken from each group.
Stratified sampling
A sample is selected from a a population such that each possible sample of size n has the same probability of being selected.
Simple random sampling
When a histogram has a longer tail to the left, it is said to be
skewed to the left
A numerical measure of linear association between two variables is the
correlation coefficient
The assembly time for a product is uniformly distributed between 6 to 10 minutes.
The probability of assembling the product between 8 to 10 minutes is
.50
Consider the random variable x that follows a normal distribution, with a mean of 22 and a standard deviation of 8. If x = 32, then the corresponding standardized value, z, is equal to
1.25
The interquartile range is
the difference between the third quartile and the first quartile
In hypothesis testing,
the smaller the Type I error, the larger the Type II error will be
For a sample of retired NFL players, data are collected on the number of concussions each experienced during his career. This study would be considered
observational
To compare the production techniques used by foreign and local firms in Brazil, a random sample of 80 foreign firms and a random sample of 80 local firms are selected. The study
an independent samples design.
The purpose of statistical inference is to provide information about the
population based upon information contained in the sample
A normal distribution with a mean of 0 and a standard deviation of 1 is called
a standard normal distribution
The counting rule that is used for counting the number of experimental outcomes when n objects are selected from a set of N objects where order of selection is important is called
permutation
A committee of 4 is to be selected from a group of 12 people. How many possible different committees can be selected?
495
Assume your favorite basketball team has 3 games left to finish the season. The outcome of each game can be a win or a loss. The number of possible outcomes is
8
A simple random sample of 6 computer programmers in Houston, Texas revealed the gender of the programmers and the following information about their weekly incomes.
Programmer
Weekly Income
Gender
A
$250
M
B
270
M
C
285
F
D
240
M
E
255
M
F
290
F
Determine
0.667
The difference between the largest and the smallest data values is the
range
Consider the data in the attached file. Calculate the correlation between y and x.
Express your answer as a decimal rounded to four places.
0.3453
Some hotels ask their guests to rate the hotel's services as excellent, very good, good, and poor. This is an example of the
ordinal scale
Bayes' theorem is used to compute
the posterior probabilities
When the data are skewed to the right, the measure of Skewness will be
positive
In a questionnaire, respondents are asked to mark their gender as male or female. Gender is an example of the
nominal scale
If two independent large samples are taken from two populations, the sampling distribution of the difference between the two sample means
can be approximated by a normal distribution
The sum of the probabilities of two complementary events is
1.0
The attached spreadsheet provides a probability distribution for the random variable x. Calculate the mean of x. Round your answer to one decimal place.
6.0
A bank has kept records of the checking balances of its customers and determined that the average daily balance of its customers is $300 with a standard deviation of $48. A random sample of 144 checking accounts is selected. What is the probability that t
.9772
For a population with any distribution, the form of the sampling distribution of the sample mean is
always normal for large sample sizes
A random sample of 64 SAT scores of students applying for merit scholarships showed an average of 1400 with a sample standard deviation of 240.
The lower bound of a 95% confidence interval for the SAT scores is
1340.05
The coefficient of correlation ranges between
-1 and +1
The value added and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the
margin of error
Of ten banks receiving TARP funds, only three actually increased lending. If you select four banks for further analysis, what is the probability that exactly one of the banks selected were in the group that had increased lending? Use the attached spreadsh
0.5
If A and B are independent events with P(A) = 0.38 and P(B) = 0.55, then P(A | B) =
(Use the attached spreadsheet if necessary for calculations.)
.38
A Federal Communications Commission economist conducts a statistical study to test her hunch that consumers' mean monthly phone bill increases following the purchase of an iPhone. For each statement below indicate whether the statement is the null hypothe
Null hypothesis
Consumers' mean monthly phone bill decreases following the purchase of an iPhone.
Neither
Consumers' mean monthly phone bill increases following the purchase of an iPhone.
Alternate hypothesis
Consumers' mean monthly phone bill increases or stays the same following the purchase of an iPhone.
Neither
The management of a department store is interested in estimating the difference between the mean credit purchases of customers using the store's credit card versus those customers using a national major credit card. You are given the following information
15
In a five number summary, which of the following is not used for data summarization?
the mean
If you are conducting an experiment where the probability of a success is .02 and you are interested in the probability of 4 successes in 15 trials, the correct probability function to use is the
binomial probability function
The intersection of two mutually exclusive events
must always be equal to 0
In general, higher confidence levels provide
wider confidence intervals
Temperature is an example of a variable that uses
the interval scale
For a given level of Type I error, as the sample size increases, the level of Type II error
decreases
As the test statistic for an upper tail hypothesis test becomes larger, the p-value
gets smaller
As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution
becomes smaller
Which of the following best describes the form of the sampling distribution of the sample proportion?
It is approximately normal as long as np (5 and n(1-p) 5)
Use attached spreadsheet to answer this question.
The random variable x is the number of occurrences of an event over an interval of ten minutes. It can be assumed that the probability of an occurrence is the same in any two-time periods of an equal lengt
.0771
When each data value in one sample is matched with a corresponding data value in another sample, the samples are known as
matched samples
In order to determine whether or not there is a significant difference between the hourly wages of two companies, the following data have been accumulated.
Company 1 Company 2
n1 = 80 n2 = 60
= $10.80 = $10.00
= $2.00 = $1.50
The null hypothesis for this
m1 - m2 = 0
Refer to Question 1. The point estimate of the difference between the means is
0.8
Refer to Question 1. The test statistic has a value of
2.7
Refer to Question 3. The p-value is
0.007
Refer to Question 1. If the level of significance is 0.05, the absolute value of the critical value for the hypothesis test is
1.96
Refer to Question 4 or 5. If alpha is .05, the correct conclusion is
reject the null hypothesis
The following information was obtained from independent random samples.
Assume normally distributed populations.
Sample 1
Sample 2
Sample Mean
45
42
Sample Variance
85
90
Sample Size
10
12
The point estimate for the difference between the means of the two
3
Refer to Question 7. The standard error of is
4.0
Refer to Questions 7 & 8. We are interested in testing whether the average of population 1 is greater than the average of population 2. What is the value of the test statistic?
0.75
Refer to Question 9. The p-value at 19 degrees of freedom is
0.23
Refer to Question 10. If alpha is .05, the correct conclusion is
do not reject the null hypothesis
The results of a recent poll on the preference of teenagers regarding the types of music they listen to are shown below.
Music Type
Teenagers Surveyed
Teenagers Favoring
This Type
Pop
800
384
Rap
900
450
The point estimate for the difference between the p
-0.02
An insurance company selected samples of clients under 18 years of age and over 18 and recorded the number of accidents they had in the previous year. The results are shown below.
Under Age of 18 Over Age of 18
n1 = 500 n2 = 600
Number of accidents = 180
pu - po = 0
If we are interested in testing whether the proportion of items in population 1 is larger than the proportion of items in population 2, the
alternative hypothesis should state P1 - P2 > 0
Refer to Question 1. The pooled proportion is
.300
Refer to Questions 1 and 2. Determine the value of the standard error of the difference in the proportions. Round your answer to four decimal places.
.0277
Refer to Questions 1, 2 and 3. The test statistic is
3.96
Refer to Question 4. The p-value is
less than 0.001
Refer to Questions 1 and 5. If alpha is .05, the correct conclusion is
do not reject the null hypothesis