Statistics Final
Recently, an analyst in a company's marketing department surveyed customers regarding how often they buy a particular product. One customer indicated that she purchased the product 17 times in the last six months, but the analyst recorded the response as 71 times. This is an example of observer bias.
False
Suppose a coin is flipped twice. The event of getting heads on the first toss and the event of getting heads on the second toss could be said to be mutually exclusive.
False
The Colbert Real Estate Agency has determined the number of home showings given by its agents is the same each day of the week. Then the variable, number of sowings, is a continuous distribution.
False
It is possible for a set of data to have multiple modes as well as multiple medians, but there can be only one mean.
False
Mutually exclusive means that the occurrence of event A has no effect on the probability of the occurrence of event B, and independent means the occurrence of event A prevents the occurrence of event B.
False
Recently an article in newspaper stated that 75 percent of the households in the state had incomes of $20,200 or below. Given this input, it is certain that mean household income is less than $20,200.
False
The Cranston Company recently met with a group of its customers to ask questions about the service and products provided by the company. The data collected in this process would be an example of data collected through direct observation.
False
The difference between a scatter plot and a scatter diagram is that the scatter plot has the independent variable on the x-axis while the independent variable is on the Y-axis in a scatter diagram.
False
The interquartile range is the difference between the mean and the median.
False
The number of no-shows each day for dinner reservations at the Cottonwood Grille is a discrete random variable with the following probability distribution: Based on this information, the standard deviation for the number of no-shows is about .36 customers
False
The second quartile for a set of data will have the same value as the 50th percentile only when the data are symmetric.
False
The sign on the intercept coefficient in a simple regression model will always be the same as the sign on the correlation coefficient.
False
The symbol μ is used to represent the sample mean.
False
When university newspaper reporters take a poll of students by standing outside of the nearest pub to survey students about the university offering upgraded food options, the sampling method used is called a random sample.
False
You are given the following data: 23, 34, 11, 40, 25, 47 Assuming that the data reflect the population of interest, the mean of the population is 36.00
False
You are given the following sample data for two variables: Based upon these sample data and testing at the .05 level of significance, the critical value for testing whether the population correlation coefficient is equal to zero is t=2.2622.
False
The results of a census of 2,500 employees of a mid-sized company with 401(k) retirement accounts are as follows: Suppose researchers are going to sample employees from the company for further study. Compute the probability that a randomly selected employee will be female with an account balance between $100,000 and $150,000.
NOT d.) .4040
Given a regression equation y = 16 + 2.3x we would expect that an increase in x of 2.0 would lead to an average increase of y of 4.6.
True
If after graphing the data for a quantitative variable of interest, you notice that the distribution is highly skewed in the positive direction, the measure of central location that would likely provide the best assessment of the center would be the median.
True
If you were planning to take a small group out to dinner on a Thursday evening and you were considering whether to call ahead for a reservation, the method of probability assessment you would most likely use to assess the chances of being able to get in for dinner without having a reservation would be subjective assessment.
True
According to the annual report issued by Wilson & Associates, an investment firm in Bowling Green, the stocks in its Growth Fund have generated an average return of 8% with a standard deviation of 2%. The stocks in the Specialized Fund have generated an average return of 18% with a standard deviation of 6%. 1.) Based on the data provided, which of these funds has exhibited greater relative variability? Use the proper statistical measure to make your determination. 2.) Suppose an investor who is very risk averse (having a strong dislike of taking risks) is interested in one of these two funds. Based strictly on the measure of variability, which fund would you recommend? Discuss.
1.) Based on the data provided, the Specialized Fund has exhibited greater relative variability. (.245) 2.) Based strictly on the measure of variability, the fund that I'd recommend to an investor who is very risk averse is the Growth Fund. This is because The Growth Fund has a lower variance (.1414) and therefore, is not as much of a risk when compared to the Specialized Fund.
For each variable below, indicate the level of measurement (nominal, ordinal, interval, or ratio): 1.) Age of the award winner for best actress 2.) Method of payment used when buying a new laptop 3.) The ideal cooking temperature for a chicken pot pie 4.) Faculty ranks (professor, associate professor, assistant professor, or instructor)
1.) ratio 2.) nominal 3.) interval 4.) ordinal
Give the name of the kind of statistical sampling technique that was most likely used in each of the cases described below (simple random sampling, stratified sampling, systematic sampling, cluster sampling): 1.) A news organization poll of 2,000 people to determine the president's approval rating 2.) A poll taken of each of a motorcycle manufacturer's dealership in a region in July to determine an estimate of the average number of the manufacturer's motorcycles not yet sold by all of the manufacturer's dealerships in the country 3.) A quality-assurance procedure within a plant that manufactures corn chips tests every 2,000th bag of corn chips produced to make sure the bag is sealed properly 4.) A sampling technique in which a random sample from each tax brackets is obtained by a national tax collection agency
1.) simple random sampling 2.) cluster sampling 3.) systematic sampling 4.) stratified sampling
What range of time might the restaurant say is the most frequent speed of service?
91-99 seconds
A cellular phone service provider believes that there is a negative correlation between the minutes used by its customers and the age of the customer. To test this, the following would be the appropriate null and alternative hypotheses: Ho: p = 0.0 Ha: p = 0.0
False
A correlation of -.9 indicates a weak linear relationship between the variables.
False
A distribution is said to be symmetric when the sample mean and the population mean are equal.
False
A pie chart is almost always constructed when the variable of interest is qualitative.
False
A product that is produced at Ramsey Manufacturing goes through three steps to be built. At step one, the components are assembled by technicians. At step two, the product is sanded, and at step three the product is painted. The product can become defective if any of these three steps is performed incorrectly. The three steps are done by different people in different locations. We let D1 = defect introduced at step 1, D2 = defect introduced at step 2, and D3 = defect introduced at step three. Based on this situation these three events would be considered to be mutually exclusive.
False
At a potato processing plant in the state of Washington, 400 potatoes have been examined for disease. Of these, four were diseased. Based on this, the plant manager has stated that the probability of finding a diseased potato is 0.01. He is applying subjective probability to arrive at this 0.01 value.
False
Both a scatter plot and the correlation coefficient can distinguish between a curvilinear and a linear relationship.
False
During the past week, of the 250 customers at the Dairy Queen who ordered a Blizzard, 50 ordered strawberry. This means that of the next five Blizzard customers, exactly one will order strawberry.
False
For a continuous distribution the total area under the curve is equal to 100
False
If a manager were interested in assessing the probability that a new product will be successful in a New Jersey market area, she would most likely use relative frequency of occurrence as the method for assessing the probability.
False
If a random variable is discrete, it means that the outcome for the random variable can take on only one of two possible values.
False
If the Viking Sales Company plans to display the sales for each of its six major products for the year 2001, an effective chart to do this would be a histogram.
False
If two variables are uncorrelated, the sample correlation coefficient will be r = 0.00.
False
In an unstructured interview the questions are scripted.
False
In constructing a frequency distribution for the savings account balances for customers at a bank, the following class boundaries might be acceptable if the minimum balance is $5.00 and the maximum balance is $18,700: $0.00-$5,000 $5,000-10,000 $10,000-$15,000 $15,000-$20,000
False
A construction company has found it has a probability of .10 of winning each time it bids on a project. The probability of winning a given number of projects out of 12 bids could be determined with a binomial distribution.
True
A light bulb manufacturer wants to advertise the average life of its light bulbs so it tests a subset of light bulbs. This is an example of inferential statistics.
True
A manufacturing manager has developed a table that shows the average production volume each day for the past three weeks. The average production level is an example of a numerical measure.
True
A recent study of students at the university contained data on year in school and student age. An appropriate tool for analyzing the relationship between these two variables would be a joint frequency distribution.
True
A study of 2000 Verizon cellphone customers listed the annual incomes of the customers as well as other variables. The lowest income was $25,000 and the highest income was $145,000. To develop a frequency distributions with 6 classes, the smallest value that the class width can be is 20k.
True
A university study indicated that a correlation of -.7 was found between the number of hours spent playing video games and a student's gpa. This means that the more time spent playing video games, the lower the overall gpa.
True
In a study involving car owners, one question asked the owner for the number of miles driven last year. A second question asked the owner for the age of the vehicle. A joint frequency distribution would be useful for determining whether newer cars tend to be driven more miles than older cars.
True
One example of a difference between discrete random variables and continuous random variables is that in a discrete distribution P(x>2) while in a continuous distribution P(x>2) is treated the same s P(x>-2)
True
One of the differences between a stem and leaf diagram and a histogram is that even for variables involving a large number of different values, the stem and leaf diagram shows the individual data values whereas the histogram requires you to group the data and lose the individual values.
True
Recently a survey was conducted in which customers of a large insurance company were asked to indicate the number of speeding tickets they had received in the past three years. The minimum value in the data was zero and the largest was six tickets. If you wished to illustrate the proportion of people who had three or fewer tickets, you would most likely construct a cumulative relative frequency distribution.
True
Recording vehicle type as sedan, minivan, pick-up truck, etc. is an example of qualitative data.
True
Sawyer & company is a law firm in Dallas, Texas. Recently, the administrative manager prepared a report for the managing partners that showed the number of court cases handled by the firm monthly over the past three years. It was appropriate for her to use a line chart in this case.
True
Some of the most common methods of collecting data include experiments, telephone surveys, mail questionnaires, direct observations, and personal interviews.
True
The Argon Construction Company has the opportunity to enter into a contract to remodel a building. The following table shows the probability distribution for the profit that could occur if it takes the contract: Based on this information, the expected profit for the company if it takes the contract is $67,000.
True
The Argon Construction Company has the opportunity to enter into a contract to remodel a building. The following table shows the probability distribution for the profit that could occur if it takes the contract: Based on this information, the probability of profit being at least $80,000 is .85.
True
The Argon Construction company has the opportunity to enter into a contract to remodel a building. The following table shows the probability distribution for the profit that could occur if it takes the contract: Based on this information, the probability of profit being <$80,000 = .55
True
The Parks and Recreation manager for the city of Detroit recently submitted a report to the city council in which he indicated that a random sample of 500 park users indicated that the average number of visits per month was 4.56. This value should be viewed as a statistic by the city council.
True
The appropriate number of classes should generally be between 5 and 20.
True
The credit card balances for customers at State Bank and Trust has a mean equal to $800 and a standard deviation equal to $60.00. Kevin Smith's balance is $1,352. Based on this, his standardized value is 9.20.
True
The following probability distribution was subjectively assessed for the number of sales a salesperson would make if he or she made five sales calls in one day. Given this distribution, the probability that the number of sales is 2 or 3 is .50.
True
The following probability distribution was subjectively assessed for the number of sales a salesperson would make if he or she made five sales calls in one day. When the salesperson makes a sale, there are three possible sales levels: large, medium, and small. The probability of a large sale is .20 and the chance of medium sale is .60. The probability on a given day that the salesperson will make one sale and that it is medium is .09.
True
The only two types of random variables are discrete and continuous random variables.
True
The random variable, number of customers entering a store between 9am and noon, is an example of a discrete random variable.
True
The scatter plot is a two dimensional graph that is used to graphically represent the relationship between two variables.
True
Typically, a continuous random variable is one whose value is determined by measurement instead of counting.
True
When a construction company bids on a contract, the events will be win or lose. The closer the probability is too .50, the greater the uncertainty about whether the company will win or lose the bid.
True
When people fail to respond to a survey, the data collection process may suffer from nonresponse bias.
True
When the production manager selects a sample of items that have been produced on her production line and computes the proportion of those items that are defective, the proportion is referred to as a statistic.
True
When using the binomial distribution, the maximum possible number of success is the number of trials.
True
The summaries of data, which may be in forms of tabular, graphical, or numerical, are referred to as: a.) report generation b.) descriptive statistics c.) inferential statistics d.) statistical inference
b.) descriptive statistics
Fifty chief executive officers of small to medium-sized companies were classified according to their gender and functional background as shown in the table below: Using the relative frequency approach, a.) If a chief executive is randomly selected from this group, what is the probability that the executive is a female? b.) If a chief executive is randomly selected from this group, what is the probability that ht executive is a male and has a Finance functional background? c.) If a chief executive is randomly selected from this group d.) e.)
a.) 18/50 = .36 = 36% b.) 11/50 = .22 = 22% c.) ? d.) 3/20=.15 = 15% e.) No, the following are not mutually exclusive because the events can occur at the same time. It is possible for the CEO selected to both be a male and have a background in marketing. The probability that both happen would be 4/50 = 8%.
The manager of a Miami restaurant recently selected a random sample of 18 customers and kept track of how long the customers were required to wait from the time they arrived at the restaurant until they were actually served diner. The following data were recorded, with time measured in minutes: 34, 24,43,56,74,20,19,33,55,43,54,34,27,34,36,24,54,39 a.) Use your calculator to compute the mean waiting time for this sample of customers b.) Use your calculator to compute the median waiting time for this sample of customers. c.) Based on your results in parts a.) and b.) above, would you say the waiting time for customers has a symmetric or a skewed distribution? d.) The manager is considering giving a complimentary drink to customers whose waiting time is longer than the third quartile. Determine the minimum number of minutes a customer would have to wait in order to receive a complimentary drink.
a.) 39.05 min. b.) 35 min. c.)Based on my results in parts a.) and b.) above, I would say that the waiting time for customers has a distribution that is skewed slightly to the right. d.) The minimum number of minutes a customer would have to wait in order to receive a complimentary drink is 54 minutes.
When a marketing manager surveys a few of the customers for the purpose of drawing a conclusion about the entire list of customers, she is applying: a.) inferential statistics b.) descriptive statistics c.) numerical measures d.) quantitative models
a.) Inferential statistics
One of the advances that have helped to alleviate carpal tunnel syndrome is ergonomic keyboards. The ergonomic keyboards may also increase typing speed. Ten administrative assistants were chosen to type on both standard and ergonomic keyboards. The resulting typing speeds follow: a.) Let x=ergonomic and y=standard. Produce a scatter plot of the typing speeds of administrative assistants using ergonomic and standard keyboards. Comment on the... b.) Use your calculator to compute the sample correlation coefficient of the typing speeds of administrative assistants using ergonomic and standard keyboards. Comment... c.) Conduct a hypothesis test to determine if a positive correlation exists between the typing speeds of admin... Use a significance level of a = .05.
a.) The scatter plot is not very strong. There is no linear relationship between the two variables. b.) r= .71 t= c.) p-value .845 ????
A stem and leaf diagram is an alternative to using: a.) a histogram b.) an ogive c.) a pie chart d.) a bar chart
a.) a histogram
A consumer products company is considering introducing a new product nationally. To help make the decision, it first conducts a test market by selling the product for a few months in one city. This is an example of: a.) hypothesis testing b.) estimation c.) charts and graphs d.) descriptive statistics
a.) hypothesis testing
A line chart is most appropriate for: a.) time-series data b.) cross-sectional data c.) ordinal level data d.) nominal level data
a.) time-series data
General Electric Corporation tracks employee turnover annually. It currently has a data set that contains turnover for the past 20 years. What type of data does it have? a.) time-series data b.) nominal data c.) cross-sectional data d.) ordinal
a.) time-series data
The Jack In The Box franchise in Bangor, Maine, has determined that the chance a customer will order a soft drink is .90. The probability that a customer will order a hamburger is .60. The probability that a customer will order french fries is .50. The restaurant has also determined that if a customer orders a hamburger, the probability the customer will also order fries is .80. Determine the probability that the order will include a hamburger and fries.
b.) .48
Assuming you have data for a variable with 2,000 values, using the 2^k > n guideline, what is the least number of groups that should be used in developing a grouped data frequency distribution? a.) 9 b.) 11 c.) 12 d.) 13
b.) 11
A small company has 7 employees. The numbers of years these employees have worked for this company are shown as follows: 4, 14, 3, 16, 9, 8, 16. Based upon this information, the mode number of years that employees have been with this company is: a.) 10 b.) 16, c.) 9 d.) 2
b.) 16
A value computed from a population is called: a.) a point estimate b.) a parameter c.) a statistic d.) a real number
b.) a parameter
The human resources department at a major high tech company recently conducted an employee satisfaction survey of 100 of its 3000 employees. Data were collected on such variables as age, gender, marital status, current salary, level of overall satisfaction on a scale from 1 to 5, number of years with the company, and job title. Which of the variables listed are considered to be ratio level data? a.) job title b.) age and years with the company c.) gender and marital status d.) none of the variables is ratio level
b.) age and years with the company
The asking price for homes on the real estate market in Baltimore has a mean value of $286,455 and a standard deviation of $11,200. The mean and standard deviation in asking price for homes in Denver are $188,468 and $8,230, respectively. Recently, one home sold in each city where the asking price for each home was $193,000. Assuming that both distributions are bell-shaped, which of the following statements is true?
b.) the Denver home has a higher standard z-value
Todd Lindsey & Associates, a commercial real estate company located in Boston, owns six office buildings in the Boston area that it leases to businesses. The lease price per square foot differs by building due to location and building amenities. Currently, all six buildings are fully leased at the prices shown here. Price per Square Foot Number of Square Feet Building 1 $75 125,000 Building 2 $85 37,500 Building 3 $90 77,500 Building 4 $45 35,000 Building 5 $55 60,000 Building 6 $110 130,000 Compute the weighted average (mean) price per square foot for these buildings.
c.) 83.25
In analyzing the relationship between two variables, a scatter plot cannot be used to detect which of the following?
c.) a causal relationship
Which of the following cannot be shown effectively with a histogram? a.) a relative frequency distribution b.) a frequency distribution c.) a joint frequency distribution d.) the center, shape, and spread of a distribution
c.) a joint frequency distribution
Which one of the following is not statistical sampling? a.) simple random sample b.) cluster sampling c.) convenience sampling d.) stratified random sampling
c.) convenience sampling
The term that is given when two variables are correlated but there is no apparent connection between them is:
c.) spurious correlation
Which of the following measures is not affected by extreme values in the data?
c.) the median
If the population correlation between two variables is determined to be -.70, which of the following is known to bet true?
c.) there is a fairly strong negative linear relationship between the two variables
Which of the following is a reason for construction a joint frequency distribution? a.) too measure the spread between the two variables b.) to show the average of two variables c._ to help analyze the relationship between the two variables d.) too determine the trend between the two variables
c.) to help analyze the relationship between two variables
A study was recently performed by the Internal Revenue Service to determine how much tip income waiters and waitresses should make based on the size of the bill at each table. A random sample of bills and resulting tips were collected. These data are shown as follows: Based upon these data, what is the approximate predicted value for tips if the total bill is $100?
d.) $20.61
A small company hs 7 employees. The numbers of years these employees have worked for this company are shown as follows: 4, 14, 3, 16, 9, 8, 16. Based upon this information, the mean number of years that employees have been with this company is: a.) 16 b.) 8.40 c.) x̅ d.) 10
d.) 10
A study was recently done in which the brand preference for breakfast cereal was analyzed against the gender of the shopper. The study consisted of 200 male shoppers and 300 female shoppers. Three different cereal brands were considered: a, b, and c. A total of 250 female shoppers preferred brand a, 25 female shoppers preferred brand c. A total of 100 shoppers preferred brand b. The number of male shoppers that preferred brand b was: a.)50 b.) 100 c.) 25 d.) 75
d.) 75
Which of the following statements is true with respect to a simple linear regression model?
d.) all of the above are true
The human resources department at a major high tech company plans to conduct an employee satisfaction study by sampling 100 employees from the 3,000 total employees. They plan to use systematic random sampling since the employee file is in alphabetic order. The first employee selected in the study should be: a.) employee 1 to 100 randomly selected b.) the 30th employee c.) the first employee d.) employee 1 to 30 randomly selected
d.) employee 1 to 30 randomly selected
When a survey uses the responses strongly disagree, disagree, neutral, agree, strongly agree, this is an example of: a.) nominal data b.) interval data c.) ratio data d.) ordinal data
d.) ordinal data
One of the major challenges for developing a good written questionnaire or telephone survey instrument is that: a.) bias cannot be controlled b.) nonresponse are too high c.) there will always be missed data d.) wording can influence responses
d.) wording can influence responses
