Which of the following is not a characteristic of the normal probability distribution?
The graph of the curve is the shape of a rectangle
The total area under the curve is always equal to 1.
99.72% of the time the random variable assumes a value within plus or minus three standard deviations of its mean
The mean is equal to the median, which is also equal to the mode.
A manufacturer wants to estimate the proportion of defective items that are produced by a certain machine. A random sample of 50 items is taken. Which Excel function would not be appropriate to construct a confidence interval estimate?
Answer (I feel this question is a bit ambiguous. The answer depends upon in what form data is given. I have chosen the best answer)
All are appropriate.
The expected value of the random variable is
the standard error
the sample size
the population mean
Ordinary arithmetic operations are meaningful
only with categorical data
only with quantitative data
either with quantitative or categorical data
with rank data
It is known that the population variance equals 484. With a 0.95 probability, the sample size that needs to be taken to estimate the population mean if the desired margin of error is 5 or less is
In a sample of 800 students in a university, 160, or 20%, are Business majors. Based on the above information, the school's paper reported that "20% of all the students at the university are Business majors." This report is an example of
The control limits for an x-bar chart are how many standard deviations above and below the process mean?
A measure of the strength of the relationship between two variables is the
coefficient of determination
slope b1 of the estimated regression line
standard error of the estimate
When the data have the properties of interval data and the ratio of two values is meaningful, the variable has which scale of measurement?
If the cost of a Type I error is high, a smaller value should be chosen for the
level of significance
If the data distribution is symmetric, the skewness is
None of the other answers is correct.
A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information.
Today Five Years Ago
s2 112.5 54
n 45 36
Refer to Exhibit 10-3. The 95% confidence interval for the difference between the two population means is
-9.92 to -2.08
-3.92 to 3.92
-13.84 to 1.84
-24.228 to 12.23
A researcher has collected the following sample data. The mean of the sample is 5.
3 5 12 3 2
Refer to Exhibit 3-2. The interquartile range is
A sample of five Fortune 500 companies showed the following revenues ($ millions): 7505.0, 2904.7, 7208.4, 6819.0, and 19500.0. Based on this information, which of the following statements is correct?
An estimate of the average revenue for all Fortune 500 companies is 8787.42 ($ millions).
The average revenue for all Fortune 500 companies is 8787.42 ($ millions).
Over half of all Fortune 500 companies earn at least 7208.4 ($ millions) in revenues.
If five other Fortune 500 companies were chosen, the average revenue would be 8787.42 ($ millions).
For the standard normal probability distribution, the area to the left of the mean is
any value between 0 to 1
For any continuous random variable, the probability that the random variable takes on exactly a specific value is
any value between 0 to 1
Excel's __________ can be used to construct a frequency distribution for qualitative data.
Excel's NORMSINV function can be used to compute
cumulative probabilities for a standard normal z value
the standard normal z value given a cumulative probability
cumulative probabilities for a normally distributed x value
the normally distributed x value given a cumulative probability
The interquartile range is the difference between the
first and second quartiles
first and third quartiles
second and third quartiles
second and fourth quartiles
Independent simple random samples are taken to test the difference between the means of two populations whose variances are not known. The sample sizes are n1 = 32 and n2 = 40. The correct distribution to use is the
t distribution with 72 degrees of freedom
t distribution with 71 degrees of freedom
t distribution with 70 degrees of freedom
Which of the following is an example of qualitative data?
social security number
score on a multiple-choice exam
height, in meters, of a diving board
number of square feet of carpet
A frequency distribution is
a tabular summary of a set of data showing the fraction of items in each of several nonoverlapping classes
a graphical form of representing data
a tabular summary of a set of data showing the number of items in each of several nonoverlapping classes
a graphical device for presenting categorical data
A tabular summary of a set of data showing the fraction of the total number of items in several nonoverlapping classes is a
relative frequency distribution.
cumulative frequency distribution.
The number of sick days taken (per month) by 200 factory workers is summarized below.
Number of Days Frequency
0 - 5 120
6 - 10 65
11 - 15 14
16 - 20 1
Refer to Exhibit 2-3. The number of workers who took more than 10 sick days per month
A graphical presentation of a frequency distribution, relative frequency distribution, or percent frequency distribution of quantitative data constructed by placing the class intervals on the horizontal axis and the frequencies on the vertical axis is a
The sample statistic s is the point estimator of
The birth weight of newborns, measured in grams, is an example of
either categorical or quantitative data
neither categorical nor quantitative data
A control chart that is used to monitor the range of the measurements in a sample is
a p chart
an x-bar chart
an R chart
an np chart
The empirical rule states that, for data having a bell-shaped distribution, the percentage of data values being within one standard deviation of the mean is approximately
The relative frequency of a class is computed by
dividing the midpoint of the class by the sample size.
dividing the frequency of the class by the midpoint.
dividing the sample size by the frequency of the class.
dividing the frequency of the class by the sample size.
When using Excel to calculate a p-value for an upper-tail hypothesis test, the following must be used
1 - NORMSDIST
Not enough information is given to answer this question.
Excel's __________ function can be used to compute the mean.
In regression analysis, the variable that is being predicted is the
None of these answers is correct.
For a standard normal distribution, a negative value of z indicates
a mistake has been made in computations, because z is always positive
the area corresponding to the z is negative
the z is to the left of the mean
the z is to the right of the mean
n = 49 H0: m = 50
= 54.8 Ha: m ¹ 50
s = 28
Refer to Exhibit 9-3. The test statistic equals
The weight of items produced by a machine is normally distributed with a mean of 8 ounces and a standard deviation of 2 ounces.
Refer to Exhibit 6-5. What is the probability that a randomly selected item will weigh more than 10 ounces?
The numbers of hours worked (per week) by 400 statistics students are shown below.
Number of hours Frequency
0 - 9 20
10 - 19 80
20 - 29 200
30 - 39 100
Refer to Exhibit 2-1. The percentage of students who work at least 10 hours per week is
A newspaper wants to estimate the proportion of Americans who will vote for Candidate A. A random sample of 1000 voters is taken. Of the 1000 respondents, 526 say that they will vote for Candidate A. Which Excel function would be used to construct a confidence interval estimate?
You are given the following information about y and x.
Refer to Exhibit 12-2. The least squares estimate of b0 equals
From a population of 200 elements, the standard deviation is known to be 14. A sample of 49 elements is selected. It is determined that the sample mean is 56. The standard error of the mean is
greater than 2
less than 2