Business Stats test 2 chap 6
A company is studying the number of monthly absences among its 125 employees. The following probability distribution shows the likelihood that people were absent 0, 1, 2, 3, 4, or 5 days last month. What is the mode of the distribution?
0 days
David's gasoline station offers 4 cents off per gallon if the customer pays in cash and does not use a credit card. Past evidence indicates that 40% of all customers pay in cash. During a one-hour period, 15 customers buy gasoline at this station. What is the probability that all 15 pay in cash?
0.0
A statistics professor receives an average of five e-mail messages per day from students. Assume the number of messages approximates a Poisson distribution. What is the probability that on a randomly selected day she will have no messages?
0.0067
A true/false test consists of six questions. If you guess the answer to each question, what is the probability of getting all six questions correct?
0.016
Sweetwater & Associates write weekend trip insurance at a very nominal charge. Records show that the probability that a motorist will have an accident during the weekend and file a claim is 0.0005. Suppose they wrote 400 policies for the coming weekend, what is the probability that exactly two claims will be filed?
0.0164
Sponsors of a local charity decided to attract wealthy patrons to its $500-a-plate dinner by allowing each patron to buy a set of 20 tickets for the gaming tables. The chance of winning a prize for each of the 20 plays is 50-50. If you bought 20 tickets, what is the chance of winning 15 or more prizes?
0.021
An insurance agent has appointments with four prospective clients tomorrow. From past experience the agent knows that the probability of making a sale on any appointment is 1 out of 5. Using the rules of probability, what is the likelihood that the agent will sell a policy to 3 of the 4 prospective clients?
0.026
Chances are 50-50 that a newborn baby will be a girl. For families with five children, what is the probability that all the children are girls?
0.031
David's gasoline station offers 4 cents off per gallon if the customer pays in cash and does not use a credit card. Past evidence indicates that 40% of all customers pay in cash. During a one-hour period, 15 customers buy gasoline at this station. What is the probability that at least 10 pay in cash?
0.033
A statistics professor receives an average of five e-mail messages per day from students. Assume the number of messages approximates a Poisson distribution. What is the probability that on a randomly selected day she will have two messages?
0.0842
David's gasoline station offers 4 cents off per gallon if the customer pays in cash and does not use a credit card. Past evidence indicates that 40% of all customers pay in cash. During a one-hour period, 15 customers buy gasoline at this station. What is the probability that more than 8 and less than 12 customers pay in cash?
0.092
The following is a Poisson probability distribution with µ = 0.1. The mean of the distribution is _____.
0.1
The following is a Poisson probability distribution with µ = 0.1. The variance of the distribution is ______.
0.1
What is the mean of the distribution? To find the mean: µ = 0(.90) + 1(.09) + 2(.007) + 3(.003)
0.113
In a large metropolitan area, past records revealed that 30% of all the high school graduates go to college. From 20 graduates selected at random, what is the probability that exactly 8 will go to college?
0.114
What is the variance of the distribution? To find the variance: σ2 = (0 - .113)2(.900) + (1 - .113)2(.009) + (2 - .113)2(.007) + (3 - .113)2(.003)
0.132
The marketing department of a nationally known cereal maker plans to conduct a national survey to find out whether or not consumers of flake cereals can distinguish one of their favorite flake cereals. To test the questionnaire and procedure to be used, eight persons were asked to cooperate in an experiment. Five very small bowls of flake cereals were placed in front of a person. The bowls were labeled A, B, C, D and E. The person was informed that only one bowl contained his or her favorite flake cereal. Suppose that the eight persons in the experiment were unable to identify their favorite cereal and just guessed which bowl it was in. What is the probability that none of the eight guessed correctly?
0.168
A statistics professor receives an average of five e-mail messages per day from students. Assume the number of messages approximates a Poisson distribution. What is the probability that on a randomly selected day she will have five messages?
0.1755
A manufacturer of headache medicine claims it is 70% effective within a few minutes. That is, out of every 100 users, 70 get relief within a few minutes. A group of 12 patients are given the medicine. If the claim is true, what is the probability that eight have relief within a few minutes?
0.231
For a binomial distribution, the mean is 0.6 and n = 2. What is π for this distribution?
0.3
A total of 60% of the customers of a fast food chain order a hamburger, French fries, and a drink. If a random sample of 15 cash register receipts is selected, what is the probability that 10 or more will show that the above three food items were ordered?
0.403
The following is a binomial probability distribution with n = 3 and π = 0.20. The variance of the distribution is _________.
0.48
Affirmative action commitments by many organizations have led to an increase in the number of women in executive positions. Satellite Office Systems has vacancies for two executives that it will fill from among four women and six men. What is the probability that no woman is selected?
1/3
Which of the following is NOT a characteristic of a binomial probability distribution?
The number of trials is limited to two.
What must you know to develop a binomial probability distribution?
The probability of success and the number of trials
Which is true for a binomial distribution?
The probability of sucess remains the same from trial to trial.
Which of the following is correct about a probability distribution?
The sum of all possible outcomes must equal 1.0, The outcomes must be mutually exclusive, The probability of each outcome must be between 0.0 and 1.0 inclusive.
A company is studying the number of monthly absences among its 125 employees. The following probability distribution shows the likelihood that people were absent 0, 1, 2, 3, 4, or 5 days last month. Given the probability distribution, which of the following predictions is correct?
There is a 0.12 probability that an employee will be absent two days per month.
A measure of the long-run average value of a random variable used to represent the central location of a probability distribution is called a(n) _____________.
discrete random variable
In a Poisson distribution, the variance is equal to ___________.
nπ
To apply a Poisson probability distribution, the mean can be computed as __________.
nπ
Which shape describes a Poisson distribution?
positively skewed
A coin is tossed four times. The following table summarizes the experiment. What is the following table called?
probability distribution
A listing of all possible outcomes of an experiment and their corresponding probabilities of occurrence is called a ____________.
probability distribution
Which one of the following is NOT a condition of the binomial distribution?
sampling atleast 10 trials.
What is the only variable in the Poisson probability formula?
x
The mean or expected value for a binomial probability distribution is _________.
μ = nπ
Data show that the weight of an offensive linesman may be any weight between 200 and 350 pounds. The distribution of weight is based on a ______________.
continuous random variable
What kind of distributions are the binomial and Poisson probability distributions?
discrete
A farmer who grows genetically engineered corn is experiencing trouble with corn borers. A random check of 5,000 ears revealed the following: Many of the ears contained no borers. Some ears had one borer; A few had two borers, and so on. The distribution of the number of borers per ear approximated the Poisson distribution. The farmer counted 3,500 borers in the 5,000 ears. What is the probability that an ear of corn selected at random will contain no borers?
0.4966
For a binomial distribution, the mean is 4.0 and n = 8. What is π for this distribution?
0.5
Carlson Jewelers permits the return of their diamond wedding rings, provided the return occurs within two weeks of the purchase date. Their records reveal that 10% of the diamond wedding rings are returned. Five different customers buy a wedding ring. What is the probability that none of the customers return a ring?
0.590
On a very hot summer day, 5% of the production employees at Midland States Steel are absent from work. The production employees are randomly selected for a special in-depth study on absenteeism. What is the probability of randomly selecting 10 production employees on a hot summer day and finding that none of them are absent?
0.599
The following is a binomial probability distribution with n = 3 and π = 0.20. The mean of the distribution is _______.
0.60
What is the variance of the distribution? To find the variance: σ2 = (0 - 2.1)2(.027) + (1 - 2.1)2(.189) + (2 - 2.1)2(.441) + (3 - 2.1)2(.343
0.63
A company is studying the number of monthly absences among its 125 employees. The following probability distribution shows the likelihood that people were absent 0, 1, 2, 3, 4, or 5 days last month. What is the mean number of days absent?
0.72
Judging from recent experience, 5% of the computer keyboards produced by an automatic, high-speed machine are defective. If six keyboards are randomly selected, what is the probability that none of the keyboards are defective?
0.735
A tennis match requires that a player win three of five sets to win the match. If a player wins the first two sets, what is the probability that the player wins the match, assuming that each player is equally likely to win each set?
0.875
What is the variance of the distribution? To find the variance: σ2 = (0 - 1.604)2(.13) + (1 - 1.604)2(.346) + (2 - 1.604)2(.346) + (3 - 1.604)2(.154) + (4 - 1.604)2(.026)
0.964
A machine shop has 100 drill presses and other machines in constant use. The probability that a machine will become inoperative during a given day is 0.002. During some days, no machines are inoperative, but on other days, one, two, three, or more are broken down. What is the probability that fewer than two machines will be inoperative during a particular day?
0.9824
A company is studying the number of monthly absences among its 125 employees. The following probability distribution shows the likelihood that people were absent 0, 1, 2, 3, 4, or 5 days last month. What is the standard deviation of the number of days absent?
1.0778
A company is studying the number of monthly absences among its 125 employees. The following probability distribution shows the likelihood that people were absent 0, 1, 2, 3, 4, or 5 days last month. What is the variance of the number of days absent?
1.1616
What is the mean of the distribution? To find the mean: µ = 0(.13) + 1(.346) + 2(.346) + 3(.154) + 4(.026)
1.604
If the variance is 3.6 grams, what is the standard deviation?
1.897
What is the mean of the distribution? To find the mean: µ = 0(.027) + 1(.189) + 2(.441) + 3(.343)
2.1
The probability distribution for the number of automobiles lined up at a Lakeside Olds dealer at opening time (7:30 a.m.) for service is: On a typical day, how many automobiles should Lakeside Olds expect to be lined up at opening time?
2.85
Affirmative action commitments by many organizations have led to an increase in the number of women in executive positions. Satellite Office Systems has vacancies for two executives that it will fill from among four women and six men. What is the probability that at least one woman is selected?
2/3
A new car was put into production. It involved many assembly tasks. Each car was inspected at the end of the assembly line and the number of defects per unit was recorded. For the first 100 cars produced, there were 40 defective cars. Some of the cars had no defects, a few had one defect, and so on. The distribution of defects followed a Poisson distribution. Based on the first 100 cars produced, about how many out of every 1,000 cars assembled should have one or more defects?
About 330
David's gasoline station offers 4 cents off per gallon if the customer pays in cash and does not use a credit card. Past evidence indicates that 40% of all customers pay in cash. During a one-hour period, 15 customers buy gasoline at this station. This situation is an example of what type of discrete probability distribution?
Binomial probability distribution
In which of the following discrete distribution does the probability of a success vary from one trial to the next?
Hypergeometric
Which of the following is a requirement for use of the hypergeometric distribution?
Only two possible outcomes
The production department has installed a new spray machine to paint automobile doors. As is common with most spray guns, unsightly blemishes often appear because of improper mixture or other problems. A worker counted the number of blemishes on each door. Most doors had no blemishes; a few had one; a very few had two; and so on. The average number was 0.5 per door. The distribution of blemishes followed the Poisson distribution. Out of 10,000 doors painted, about how many would have no blemishes?
about 6,065
A type of probability distribution that shows the probability of x successes in n trials, where the probability of success remains the same from trial to trial, is referred to as a ___________.
binomial probability distribution
