Poyer Final
What statement do we make that determines if the null hypothesis is rejected?
Decision rule
A dot plot shows
The general shape of a distribution
To conduct a test of hypothesis with a small sample, we make an assumption that __________.
The population is normally distributed
True or false: A sampling distribution of the mean is a probability distribution consisting of all possible sample means of a given sample size
True
True or false: An interval estimate is a range of values in which the population parameter is likely to occur.
True
True or false: If 40 samples of size 21 were selected from a population of 22,493 we could expect the mean of the sample means and populations mean to be close but not exactly deal.
True
True or false: It is often not feasible to study the entire population because it is impossible to observe all the items in the population.
True
True or false: One factor in determining the sample size of a sample is the degree of confidence selected. This is usually 0.95 or 0.99, but it may be any degree of confidence you specify.
True
True or false: The 95% confidence interval states that 95% of the sample means of a specified sample size selected from a population will lie within plus and 1.96 standard deviations of the hypothesized population mean.
True
True or false: The standard error of the mean measures the dispersion of the sampling distributions of the sample mean.
True
True or false: We can expect some differences between sample statistics and the corresponding population parameters. This difference is called the sampling error.
True
True or false: When using the t distribution to calculate a confidence interval, we assume that the population of interest is normal or nearly normal.
True
True or false: a point estimate is a single value used to estimate a population parameter.
True
When an experiment is conducted without replace
events are dependent
For an alternative hypothesis: µ > 6,700, where is the rejection region for the hypothesis test located?
in the right or upper tail
Knowing the population standard deviation, a 95% confidence interval infers that the population mean______.
is within +_ 1.96 standard errors of the sample mean
Which of the following is a characteristic of the normal probability distribution?
it is bell shaped
The true sampling error is usually not known because ________.
mu is unkown.
A survey includes a question regarding marital status that has the following responses: single, married, divorced, separated, or widowed. What is the scale of measurement for this question?
nominal
The Equal Employment Opportunity Act requires employers to classify their employees by gender and national origin. Which level of measurement is this?
nominal
Being tracked on the internet class interval?
none apply
The mean or expected value for a binomial probability distribution is
nπ
To apply a Poisson probability distribution, the mean can be computed as __________.
nπ
which of the following is a requirement of binomial probability
only two possible outcomes
The result of a particular experiment is called a(n)
outcome
Refer to the following breakdown of responses to a survey of 'How confident are you that you saved enough to retire? what type of chart?
pie chart
A sample mean is the best point estimate of ____.
population mean
A sample standard deviation is the best point estimate of the
population standard deviation
which shape describes a poisson distribution
positively skewed
distribution graph leaning to the left is _______ __________?
positiviely skewed
the length of a bridge, measured in meters is an example of ____ ______?
quantitative data
A small sample of computer operators...?
raw data
The shape of any uniform probability distribution is
rectangular
What is the difference between sample mean and population mean called?
sampling error
The following graph is a
scatter plot
When using all the items in a population have an equal chance of being selected for a sample, the process is called_______.
simple random sampling
A method of assigning probabilities based upon judgment is referred to as the
subjective method
The distribution of Students t is
symmetrical
The probability of a Type II error is directly related to ________.
the difference between the hypothesized mean and the sample mean
Two normal distributions are compared. One has a mean of 10 and a standard deviation of 10. The second normal distribution has a mean of 10 and a standard deviation of 2. Which of the following is true?
the dispersions of the distributions are different
The upper and lower limits of a uniform probability distribution are
the maximum and minimum values of the random variable.
a stem-and-leaf display includes the following row 3 I 0 1 3 5 7 9. Assume that the data are rounded to the nearest whole number. Which statement is true?
the maximum value in the class is 39.
The sum of the deviations of each data value from this measure of central location will always be zero?
the mean
Which of the following is true regarding the normal distribution?
the mean, median, and mode are all the same
which is true for a binomial distribution
the probability of success remains the same from trial to trial
If two events are independent, then their joint probability is computed with ________?
the special rule of multiplication
when using students t to compute an interval estimate,
we assume that the samples collected from normally distributed populations
When a confidence interval for a population mean is constructed from sample data, __________.
we can conclude, for an infinite number of samples and corresponding confidence intervals, that the population mean is in a stated percentage of the intervals
The sum of the differences between sample observations and the sample mean is equal to_______________?
zero
A hypothesis regarding the weight of newborn infants at a community hospital is that the mean is 6.6 pounds. A sample of seven infants is randomly selected and their weights at birth are recorded as 9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 6.6 pounds. If α = 0.05, what is the critical t value?
±2.447
the final rankings of the top 20 NCAA college basketball teams are an example of which level of measurement?
Ordinal
if two events are mutually exclusive what does the special rule of addition state?
P(A or B) = P(A) + P(B)
What does the complement rule state?
P(A) = 1 - P(not A)
The names of the positions in a corporation, such as chief operating officer or controller, are examples of what type of variable?
Qualitative
Sales at a fast-food restaurant average $6,000 per day. The restaurant decided to introduce an advertising campaign to increase daily sales. To determine the effectiveness of the advertising campaign, a sample of 49 days of sales were taken. They found that the average daily sales were $6,300 per day. From past history, the restaurant knew that its population standard deviation is about $1,000. If the level of significance is 0.025, have sales increased as a result of the advertising campaign?
Reject the null hypothesis and conclude the mean is higher than $6,000 per day.
Sales at a fast-food restaurant average $6,000 per day. The restaurant decided to introduce an advertising campaign to increase daily sales. To determine the effectiveness of the advertising campaign, a sample of 49 days of sales were taken. They found that the average daily sales were $6,300 per day. From past history, the restaurant knew that its population standard deviation is about $1,000. If the level of significance is 0.05, have sales increased as a result of the advertising campaign?
Reject the null hypothesis and conclude the mean is higher that $6000 per day.
The mean annual incomes of certified welders are normally distributed with the mean of $50,000 and a population standard deviation of $2,000. The ship building association wishes to find out whether their welders earn more or less than $50,000 annually. A sample of 100 welders is taken and the mean annual income of the sample is $50,350. If the level of significance is 0.10, what conclusion should be drawn?
Reject the null hypothesis as the test statistic is greater than the critical value of z
If we reject the null hypothesis, what can we conclude subject to the probability, α?
Reject the null with a probability, α, of making a Type I error.
A pie chart shows the
Relative frequencies of a qualitative variable
What is another name for the alternate hypothesis?
Research hypothesis
which of the following is not a condition of the binomial distribution?
Sampling at least 10 trials
Which of the following is NOT one of the six steps in the hypothesis testing procedure? A) Formulate a decision rule B)Select a level for β C)State the null and alternate hypothesis D)Identify the test statistic
Select a level for β
when testing the safety of cars using crash tests, a sample of one or two cars is used because.
cars are destroyed
What kind of distribution are the binomial and Poisson distributions?
discrete
A university surveyed recent graduates of the English Department for their starting salaries. Four hundred graduates returned the survey. The average salary was $25,000. The population standard deviation was $2,500. What is the point estimate of the population mean?
$25,000
mean of a uniform probability distribution is
(a+b)/2
When applying the special rule of addition for mutually exclusive events, the joint probability is _____.
0
The total area of a normal probability distribution is _______.
1
Refer to the following information from a frequency distribution for "heights of college women" recorded to the nearest inch: the first two class midpoints are 62.5" and 65.5". What is the class interval?
3
refer to the following wage breakdown for a garment factory: what is the class interval?
3
Using the following statistics to describe a distribution of data, what is the interquartile range?
50 (median)
A dot plot is best applied for a data set with
50 observations
A hypothesis regarding the weight of newborn infants at a community hospital is that the mean is 6.6 pounds. A sample of seven infants is randomly selected and their weights at birth are recorded as 9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 6.6 pounds. What are the degrees of freedom?
6
The standard normal probability distribution is unique because it has _________.
A mean of 0 and a standard deviation of 1
An experiment consists of making 80 telephone calls in order to sell a particular insurance policy. The random variable in this experiment is the number of sales made. This random variable is a
discrete random varaible
What are the critical values for a two-tailed test with a 0.01 level of significance when n is large and the population standard deviation is known?
Above 2.576 and below -2.576
a normally distributed random variable has
Any value between -∞ and + ∞.
the following graph is a
Box plot
When an event's probability depends on the likelihood of another event, the probability is a
Conditional probability
The mean annual incomes of certified welders are normally distributed with the mean of $50,000 and a population standard deviation of $2,000. The ship building association wishes to find out whether their welders earn more or less than $50,000 annually. A sample of 100 welders is taken and the mean annual income of the sample is $50,350. If the level of significance is 0.05, what conclusion should be drawn?
Do not reject the null hypothesis as the test statistic is less than the critical value of z.
What is a Type II error?
Failing to reject a false null hypothesis
True or false: An interval estimate is a single value used to estimate a population parameter.
False
True or false: The population variation has little or no effect in determining the size of a sample selected from the population.
False
True or false: The standard error of the mean is also called the sampling error.
False
True or false: When deciding to collect sample information rather than collecting information from the population, the amount of time required to collect the information is unimportant.
False
The average cost of tuition and room and board at a small private liberal arts college is reported to be $8,500 per term, but a financial administrator believes that the average cost is higher. A study conducted using 350 small liberal arts colleges showed that the average cost per term is $8,745. The population standard deviation is $1,200. Let α = 0.05. What are the null and alternative hypotheses for this study?
H0: µ ≤ $8,500; H1: µ > $8,500
A hypothesis regarding the weight of newborn infants at a community hospital is that the mean is 6.6 pounds. A sample of seven infants is randomly selected and their weights at birth are recorded as 9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 6.6 pounds. What is the alternate hypothesis?
H1: µ ≠ 6.6
If the alternate hypothesis states that µ ≠ 4,000, where is the rejection region for the hypothesis test?
In both tails
What is a disadvantage of the range as a measure of dispersion?
It is based on only two observations
Define the level of significance.
It is the probability of a Type I error.
Which measures of central location are not affected by extremely small or extremely large values?
Mode and median
The members of each basketball team wear numbers on their jerseys. What scale of measurement are these numbers considered?
Nominal
The mean length of a candy bar is 43 millimeters. There is concern that the settings of the machine cutting the bars have changed. Test the claim at the 0.02 level that there has been no change in the mean length. The alternate hypothesis is that there has been a change. Twelve bars (n = 12) were selected at random and their lengths recorded. The lengths are (in millimeters) 42, 39, 42, 45, 43, 40, 39, 41, 40, 42, 43, and 42. The mean of the sample is 41.5 and the standard deviation is 1.784. Computed t = -2.913. Has there been a statistically significant change in the mean length of the bars?
Yes, because the computed t lies in the rejection region.
The distribution of students t has______.
a mean of zero and a standard deviation that depends on the sample size
Refer to the following breakdown of responses to a survey of "are you concerned about being tracked while connected to the internet"? what type of chart should be used to describe the frequency table?
a pie chart
A graphical method useful in calculating joint and conditional probability is
a tree diagram
which of the following is correct about probability distributions?
all of the answers are correct
A type of probability distribution that shows the probability of success remains the same from trial to trail, is referred to as a
binomial probability distribution
How is the t-distribution similar to the z-distribution
both continuous distributions
A survey of 25 grocery stores revealed that the average price of a gallon of milk was $2.98 with a standard error of $0.10. If both 90% and 95% confidence intervals were developed to estimate the true cost of a gallon of milk, what similarities would they have?
both use the same point estimate of the population mean.