Question 9 of 17 2.0 Points
A field researcher is gathering data on the trunk diameters of mature pine and spruce trees in a certain area. The following are the results of his random sampling. Can he conclude, at the 0.10 level of significance, that the average trunk diameter of a pine tree is greater than the average diameter of a spruce tree?
Pine trees Spruce trees
Sample size 25 35
Mean trunk diameter (cm) 55 48
Sample variance 100 140
What is the test value for this hypothesis test?
Test value: Round your answer to three decimal places.
What is the critical value?
Critical value: Round your answer to three decimal places.
Part 4 of 8 –
Question 10 of 17 1.0 Points
The marketing manager of a large supermarket chain would like to determine the effect of shelf space (in feet) on the weekly sales of international food (in hundreds of dollars). A random sample of 12 equal sized stores is selected, with the following results:
Store Shelf Space(X) Weekly Sales(Y)
1 10 2.0
2 10 2.6
3 10 1.8
4 15 2.3
5 15 2.8
6 15 3.0
7 20 2.7
8 20 3.1
9 20 3.2
10 25 3.0
11 25 3.3
12 25 3.5
Find the equation of the regression line for these data. What is the value of the coefficient of determination? Place your answer, rounded to 3 decimal places, in the blank. Do not use a dollar sign. For example, 0.345 would be a legitimate entry.
Question 11 of 17 1.0 Points
The marketing manager of a large supermarket chain would like to determine the effect of shelf space (in feet) on the weekly sales of international food (in hundreds of dollars). A random sample of 12 equal sized stores is selected, with the following results:
Store Shelf Space(X) Weekly Sales(Y)
1 10 2.0
2 10 2.6
3 10 1.8
4 15 2.3
5 15 2.8
6 15 3.0
7 20 2.7
8 20 3.1
9 20 3.2
10 25 3.0
11 25 3.3
12 25 3.5
Using the equation of the regression line for these data, predict the average weekly sales (in hundreds of dollars) of international food for stores with 13 feet of shelf space for international food.
Place your answer, rounded to 3 decimal places , in the blank. Do not use a dollar sign. For example, 2.345 would be a legitimate entry.
Part 5 of 8 –
Question 12 of 17 1.0 Points
Q-Mart is interested in comparing its male and female customers. Q-Mart would like to know if the amount of money spent by its female charge customers differs, on average, from the amount spent by its male charge customers.
To answer this question, an analyst collected random samples of 25 female customers and 22 male customers. Based on these samples, on average, the 25 women charge customers spent $102.23 and the 22 men charge customers spent $86.46. Moreover, the sample standard deviation of the amount charged by the 25 women was $93.393, and the sample standard deviation of the amount charged by the 22 men was $59.695.
Suppose, using a 10% level of significance, you wish to know if there is sufficient evidence for Q-Mart to conclude that, on average, the amount spent by women charge customers differs from the amount spent by men charge customers. That is suppose you wish to test
H0: versus H1:
Assuming that the amounts spent by female and male charge customers at Q-Mart are normally distributed, based on the procedure advocated by Bluman, what is/are the critical values that you would use to conduct this test of hypothesis? Place your answer, rounded to 3 decimal places, in the blank. If there are two critical values, place only the positive value in the blank. For example, 2.035 would be a legitimate entry.
Question 13 of 17 1.0 Points
Are America’s top chief executive officers (CEOs) really worth all that money? One way to answer this question is to look at the annual company percentage increase in revenue versus the CEO’s annual percentage salary increase in that same company. Suppose that a random sample of companies yielded the following data:
percent change for corporation 15 12 3 12 28 6 8 2
percent change for CEO 6 17 -4 12 32 -1 7 2
Do these data indicate that the population mean percentage increase in corporate revenue is greater than the population mean percentage increase in CEO salary? Use a 5% level of significance. What is the p-value associated with this test of hypothesis? Place your answer, rounded to 3 decimal places, in the blank. For example, 0.134 would be a legitimate entry.
Part 6 of 8 –
Question 14 of 17 3.0 Points
A professor gives an exam for which there are two versions, A and B. Each student in the class is given one randomly selected version of the exam. After the exam, the professor wishes to determine if there is a difference in the level of difficulty of the two versions by determining if there is a significant difference in the mean scores. Assume ? = 0.05.
Version A Version B
Sample size 45 65
Mean score 8.8 8.2
Sample variance 2.6 2.4
What is the test value for this hypothesis test?
Answer: Round your answer to two decimal places.
What is/are the critical value(s) for this hypothesis test? If there are two critical values, give only the positive value.
Answer: Round your answer to two decimal places.
What is the conclusion for this hypothesis test? Choose one.
1. There is not sufficient evidence to show that one version of the exam is more difficult than the other.
2. There is sufficient evidence to show that one version of the exam is more difficult than the other.
Answer: Enter only a 1 or 2 for your answer.
Part 7 of 8 –
Question 15 of 17 1.0 Points
When the necessary conditions are met, a two-tail test is being conducted to test the difference between two population proportions. The two sample proportions are = 0.35 and = 0.42, and the standard error of the sampling distribution of is 0.054. The calculated value of the test statistic is 1.2963.
True
False
Reset Selection
Part 8 of 8 –
Question 16 of 17 1.0 Points
A simple linear regression equation is given by y’ = 5 + 3x. The predicted value of Y when X = 3 is 5.
True
False
Reset Selection
Question 17 of 17 1.0 Points
In simple linear regression analysis, the relationship between the response variable Y and the explanatory variable X is a straight line. This means that all data points lie on the line.
True
False
Reset Selection
Question 1 of 25 1.0 Points
The difference between the first and third quartile is called the
A.unimodal range
B.mid range
C.interdependent range
D.interquartile range
Reset Selection
Part 2 of 9 –
Question 2 of 25 1.0 Points
A gumball machine contains 300 grape flavored balls, 400 cherry flavored balls, and 500 lemon flavored balls. What is the probability of getting 1 grape ball, 1 cherry ball, and 1 lemon ball if each ball was removed and then replaced before choosing the next from the machine?
A.0.0264
B.0.0531
C.0.0347
D.0.0482
Reset Selection
Question 3 of 25 1.0 Points
If P(A) = P(A|B), then events A and B are said to be
A.mutually exclusive
B.independent
C.complementary
D.exhaustive
Reset Selection
Part 3 of 9 –
Question 4 of 25 1.0 Points
Find the variance of the following probability distribution.
X P(X)
1 0.20
2 0.15
3 0.25
4 0.25
5 0.15
A.1.34
B.1.8
C.0.48
D.1.16
Reset Selection
Question 5 of 25 1.0 Points
Which term is NOT synonymous with the expected value of a discrete probability distribution?
A.mean
B.theoretical average
C.?
D.variance
Reset Selection
Question 6 of 25 1.0 Points
A multiple choice quiz consists of 6 questions, each with 4 possible answers. If a student guesses at the answer to each question, then the mean number of correct answers is
A.6.00
B.1.50
C.4.00
D.10.00
Reset Selection
Part 4 of 9 –
Question 7 of 25 1.0 Points
Find the probability, P(Z < 0.17), using the standard normal distribution.
A..8300
B..4325
C..5675
D..0675
Reset Selection
Question 8 of 25 1.0 Points
In a normal distribution, changing the standard deviation:
A.splits the distribution to two curves
B.shifts the curve left or right
C.makes the curve more or less spread out
D.makes the curve more robust
Reset Selection
Question 9 of 25 1.0 Points
If Z is a standard normal random variable, then the value z for which P(-z < Z < z) equals 0.8764 is
A.3.08
B.1.54
C.1.16
D.0.3764
Reset Selection
Question 10 of 25 1.0 Points
Given that Z is a standard normal random variable, P(-1.0 < Z < 1.5) is
A.0.0919
B.0.9332
C.0.8413
D.0.7745
Reset Selection
Question 11 of 25 1.0 Points
The normal distribution is:
A.a binomial distribution with only one parameter
B.the single most important distribution in statistics
C.a discrete distribution
D.a density function of a discrete random variable
Reset Selection
Question 12 of 25 1.0 Points
The continuous distribution characterized by a symmetric, bell-shaped curve is the:
A.Poisson distribution
B.exponential distribution
C.normal distribution
D.binomial distribution
Reset Selection
Part 5 of 9 -
Question 13 of 25 1.0 Points
A statistics professor has just given a final examination in his statistical inference course. He is particularly interested in learning how his class of 40 students performed on this exam. The scores are shown below.
77 81 74 77 79 73 80 85 86 73
83 84 81 73 75 91 76 77 95 76
90 85 92 84 81 64 75 90 78 78
82 78 86 86 82 70 76 78 72 93
What is the median score on this exam? Place your answer, rounded to two decimal places in the blank. For example, 65.78 would be a legitimate entry.
Part 6 of 9 -
Question 14 of 25 1.0 Points
It has been reported that 3% of all cars on the highway are traveling at speeds in excess of 70 mph. If the speeds of four random automobiles are measured via radar, what is the probability that at least one car is going over 70 mph? Place your answer, rounded to four decimal places, in the space.
Question 15 of 25 1.0 Points
It has been observed that electrical connectors manufactured by Jolt Electrical Supply Company last an average of 18.2 months and follow a normal distribution with a standard deviation of 1.7 months. Jolt agrees to replace any connector that fails within 19 months. Out of 500 connectors sold, how many does Jolt expect to replace, on average? Place your answer, rounded to the nearest whole number, in the blank. For example, 123 would be a legitimate answer.
Part 7 of 9 -
Question 16 of 25 1.0 Points
Suppose that a marketing firm sends questionnaires to two different companies. Based on historical evidence, the marketing research firm believes that each company, independently of the other, will return the questionnaire with a probability of 0.30. What is the probability that both questionnaires will be returned? Place your answer, rounded to 2 decimal places, in the blank. For example, 0.23 is a legitimate entry.
Question 17 of 25 1.0 Points
According to an Internet posting, 80% of adults enjoy drinking beer. If a group of 3 adults is selected at random, find the probability that none of them enjoy drinking beer.
Place your answer, rounded to three decimal places, in the blank. When entering your answer do not use any labels or symbols other than a decimal point. Simply provide the numerical value. For example, 0.123 would be a legitimate entry.
Part 8 of 9 -
Question 18 of 25 1.0 Points
A popular retail store knows that the purchase amounts by its customers is a random variable that follows a normal distribution with a mean of $30 and a standard deviation of $9.
What is the probability that a randomly selected customer will spend $20 or more at this store? Place your answer, rounded to 4 decimal places, in the blank. For example, 0.3456 would be a legitimate entry.
Question 19 of 25 1.0 Points
Mrs. Smith's reading class can read a mean of 175 words per minute with a standard deviation of 20 words per minute. The top 3% of the class is to receive a special award. Assuming that the distribution of words read per minute are normally distributed, what is the minimum number of words per minute a student would have to read in order to get the award? Place your answer, rounded to the nearest whole number, in the blank. When entering your answer do not use any labels or symbols. Simply provide the numerical value. For example, 123 would be a legitimate entry.
Question 20 of 25 1.0 Points
The length of time to complete a door assembly on an automobile factory assembly line is normally distributed with mean 6.7 minutes and standard deviation 2.2 minutes. For a door selected at random, what is the probability the assembly line time will be between 5 and 10 minutes? Place your answer, rounded to 4 decimal places, in the blank. For example, 0.1776 would be a legitimate answer.
Question 21 of 25 1.0 Points
A set of final exam scores in an organic chemistry course was found to be normally distributed, with a mean of 73 and a standard deviation of 8.
Only 5% of the students taking the test scored higher than what value? Place your answer, rounded to a whole number, in the blank. For example, 78 would be a legitimate entry.
Question 22 of 25 1.0 Points
A popular retail store knows that the purchase amounts by its customers is a random variable that follows a normal distribution with a mean of $30 and a standard deviation of $9.
What is the probability that a randomly selected customer will spend between $20 and $35 at this store? Place your answer, rounded to 4 decimal places, in the blank. For example, 0.3456 would be a legitimate entry.
Question 23 of 25 1.0 Points
A popular retail store knows that the purchase amounts by its customers is a random variable that follows a normal distribution with a mean of $30 and a standard deviation of $9.
What are the two dollar amounts, equidistant from the mean of $30, such that 90% of all customer purchases are between these values? Place your answers in the blanks provided. Do not include a dollar sign. For example, 14.25 would be a legitimate entry.
Lower value
Upper value
Part 9 of 9 -
Question 24 of 25 1.0 Points
Using the standard normal curve, the probability or area between Z = -1.50 and Z = 1.50 is 0.4332.
True
False
Reset Selection
Question 25 of 25 1.0 Points
Using the standard normal curve, the Z- score representing the 10th percentile is 1.28.
True
False