Business Statistics
If we test a small number of light bulbs from a large group, the small group is called
A sample
The measures of dispersion Variance, Standard deviation & Mean deviation, are all based on
Deviations from the mean
What type of variable is the number of auto accidents reported in a given month?
Discrete
To convert a frequency distribution to a relative frequency distribution, you would
Divide each class frequency by the sum of the class frequencies
When an experiment is conducted "without replacement"
Events are dependent
What type of distribution groups data into classes showing the number of observations in each class
Frequency distribution
The measure of central location used to determine an average annual percent increase is
Geometric mean
The midpoint of a class, or the class mark, is
Halfway between the lower and upper limits
To study the population of consumer perceptions of new technology, sampling of the population is preferred over surveying the population because
It is quicker
For any uniform probability distribution, the mean and standard deviation can be computed by knowing the
Maximum and minimum values of the random variable
The - measure of central location uses all of the observations in its calculation
Mean
The sum of the deviations of each data value from the - will always be zero
Mean
The measure of dispersion that disregards the algebraic signs (+ & -) of each difference between X and the mean is
Mean deviation
For a data set, half of the observations are always greater than the
Median
The smallest measure of central location in a positively skewed distribution
Mode
The value that occurs most often in a set of data is the
Mode
In a bar chart, the x-axis is labeled with the values of a
Qualitative variable
The difference between the largest and smallest values in a set of data
Range
What level of measurement is the prime rate of interest
Ratio
Which level of measurement is income?
Ratio
The shape of any uniform probability distribution is
Rectangular
A pie chart shows the
Relative frequencies of a qualitative variable
The difference between a sample mean and the population mean is called
Sampling error
The monthly Consumer Price Index is called
Statistic
The - approach to probability is based on a person's belief, opinion or judgment
Subjective
The main purpose of descriptive statistics is to
Summarize the data in a useful and informative manner
Statistics are used to report
The summary results of market surveys
To construct a binomial distribution, it is necessary to know
The total number of trials and the probability of success on each trial
The - diagram is useful when applying Bayes' Theorem
Tree
There are - experimental outcomes possible for the Binomial distribution
Two
To infer something about a population we
Usually take a sample from the population
In constructing a frequency polygon, class frequencies are scaled on what axis
Vertical axis
The t distribution is similar to the z distribution in all BUT one characteristics, which is that
t distribution's mean = 0 and standard deviation = 1
To compute a confidence interval, a ___ is used when the population standard deviation is known
z-statistic
Bell-shaped is a characteristic of the
Normal probability distribution
A pie chart is similar to
A relative frequency distribution
When computing weighted mean, the denominator is always the - of the -
-Sum -Weights
The average score of 100 students taking a statistics final was 70 with a standard deviation of 7. What is the probability that a student scored 90 or higher?
0.0021
A group of statistics students conducts a survey at their university to find the mean amount of time students study per week. Based on a simple random sample, they surveyed 144 students. The statistics showed that students studied an average of 20 hours per week with a standard deviation of 10 hours. What is the probability of finding a sample mean less than 18 hours?
0.0082
A true-false test consists of 6 questions. If you guess the answer to each question, what is the probability of getting all 6 questions correct?
0.016
The wildlife department has been feeding a special food to rainbow trout. Based on a large number of observations, the distribution of trout weights is normally distributed with a mean of 402.7 grams and a standard deviation 8.8 grams. What is the probability that the mean weight for a sample of 40 trout exceeds 405.5 grams?
0.0222
Chances are 50-50 that a newborn baby will be a girl. For families with 5 children, what is the probability that all are girls?
0.031
80% of the trainees are female, 20% male. 90% of the females attended college, 78% of the males attended college. A management trainee is selected at random. What is the probability that the person selected is a female who did NOT attend college?
0.08
The employees of Cartwright Manufacturing are awarded efficiency ratings. The distribution of the ratings approximates a normal distribution. The mean is 400, the standard deviation 50. What is the area under the normal curve between 400 and 482?
0.4495
What is the area under the normal curve between z = 0.0 and z = 1.79?
0.4633
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 an 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
A new computer game has been developed and 80 veteran game players will test its market potential. If 60 players liked the game, what is the probability that any veteran game player will like the new computer game?
0.75
Truck tire life is normally distributed with a mean of 60,000 miles and a standard deviation of 4,000 miles. For a set of 4 tires, what is the probability that the average tire life is between 57,000 and 63,000 miles?
0.8664
The weight of a bag of corn chips is normally distributed with a mean of 22 ounces and a standard deviation of ½ ounces. What is the probability that a bag of corn chips weighs between 20.75 and 23.25 ounces?
0.9876
The IQ test scores are normally distributed with a mean of 100 and a standard deviation of 15. Given a class with 9 students, what is the probability that the class' average IQ score is between 85 and 115?
0.9974
In a binomial experiment, what does the probability of a failure equal?
1 (probability of success)
An experiment relates to outcome, as the role of a die relates to any one value between _____ and _____
1 and 6
If the variance is 3.6 grams, what is the standard deviation
1.897
A tire manufacturer advertises, "the median life of our new all-season radial tire is 50,000 miles. An immediate adjustment will be made on any tire that does not last 50,000 miles." You purchased 4 of these tires. What is the probability that all 4 tires will wear out before traveling 50,000 miles?
1/16 or 0.0625
What is the probability that a one-spot, two-spot, or six-spot will appear face up on the throw of one die?
1/2 or 0.5
A board of directors consists of 8 men and 4 women. A 4-member search committee is randomly chosen to recommend a new company president. What is the probability that all 4 members of the search committee will be women?
1/495 or 0.002
The ages of the patients in the isolation ward of the hospital are 38, 26, 13, 41 and 22. What is the population variance?
106.8
The distribution of a sample of the outside diameters of PVC gas pipes approximates a symmetrical, bell-shaped distribution. The arithmetic mean is 14.0 inches, and the standard deviation is 0.1 inches. About 68% of the outside diameters lie between what two amounts?
13.9 and 14.1 inches
The time to fly between New York City and Chicago is uniformly distributed with a minimum of 120 minutes and a maximum of 150 minutes. What is the mean?
135 minutes
An accounting firm is planning for the next tax preparation season. From last year's returns, the firm collects a systematic random sample of 100 filings which showed an average preparation time of 90 mins with a standard deviation of 140 min. What is the standard error of the mean?
14 Min
How many permutations of the letters C and D are possible
2
A student received the following grades for the semester: History, B; Statistics, A; Spanish, C; and English, C. History and English are 5 credit courses, Statistics a 4 credit course and Spanish a 3 credit course. If 4 grade points are assigned for an A, 3 for a B and 2 for a C, what is the weighted mean for the semester grades?
2.76
The National Center for Health Statistics reported that of every 883 deaths in recent years, 24 resulted from an automobile accident, 182 from cancer and 333 from heart disease. What is the probability that a particular death is due to an automobile accident?
24/883 or 0.027
A sample revealed the ages of a popular group of musicians are 36, 29, 37, 32, 36 and 75. What is the median age?
36
Ten experts rated a newly developed chocolate chip cookie on a scale of 1 to 50. Their ratings were: 34, 35, 41, 28, 26, 29, 32, 36, 38 and 40. What is the mean deviation?
4.12
The top 10 football teams in the country, are to play every other team in the conference during the season and the team winning the most games would be the national champion. How many games would the conference commissioner have to schedule each year?
45
A random sample of 42 college graduates revealed that they worked an average of 5.5 years on the job before being promoted. The population standard deviation was 1.1 years. Using the 0.99 degree of confidence, what is the confidence interval for the population mean?
5.06 and 5.94
Mileage tests were conducted on a randomly selected sample of 100 newly developed automobile tires. The average tread wear was 50,000 miles with a standard deviation of 3,500 miles. What is the estimated average tread life in miles for the entire population of these tires?
50,000
In terms of the standard error of the mean, how wide is a 99 percent confidence interval?
50152 standard errors
A random sample of 85 group leaders and supervisors revealed that they worked an average of 6.5 years before being promoted. The population standard deviation was 1.7 years. Using the 0.95 degree of confidence, what is the confidence interval for the population mean?
6.14 and 6.86
The number of students at a local university increased from 2,500 to 5,000 in 10 years. Based on a geometric mean, the university grew at an average percentage rate of
7.1% per year
For the most recent 7 years, the U.S. Department of Education reported the following number of bachelor's degrees awarded in computer science: 4,033; 5,652; 6,407; 7,201; 8,719; 11,154; 15,121. What is the annual arithmetic mean number of degrees awarded?
8,327
15 accounting majors had an average grade of 90 on a finance exam. Seven marketing majors averaged 85, while ten finance majors averaged 93 on the same exam. What is the weighted mean for the 32 students taking the exam?
89.84
For a sampling distribution of the means, what % of the means would be between +- 2.576 standard deviations?
99%
A light bulb has an average service life of 750 hours, with a standard deviation of 50. If the service life of the light bulbs approximates a normal distribution, about what percent of the distribution will be between 600 and 900 hours?
99.7%
When referring to the normal probability distribution, there is not just one; there is
A "family" of distributions
A probability distribution
A mutually exclusive and collectively exhaustive listing of experimental outcomes that can occur by chance and their corresponding probabilities
A group of 100 students were surveyed about their interest in a new Economics major. Interest was measured in terms of high, medium, or low.What is the best way to illustrate the relative frequency of student interest?
A pie chart
A population is a collection of
All individuals, objects, or measurements of interest
The collection of one or more basic outcomes is called
An event
A random variable represents the outcomes of
An experiment
As the size of the sample increases, the shape of the distribution of sample means
Approaches a normal distribution
For a given confidence interval, what is the interpretation of a 96% confidence level?
Approximately 96 out of 100 intervals would include the true value of the population parameter
A statistic computed by summing all of the values of a distribution and dividing by the number of values is called
Arithmetic Mean
- theorem applies additional information to revise probabilities
Bayes'
Probability of success remains the same from trial to trial in - distribution
Binomial
Data measured on a nominal scale can only be classified into
Categories
A value that is typical or representative of the data is referred to as a measure of
Central location
This approach to probability assumes that the events are equally likely
Classical
A frequency polygon is a very useful graphic technique when
Comparing two or more distributions.
The performance of personal and business investments is measured as a percentage, "return on investment". What type of variable is "return on investment"?
Continuous
What type of statistics is used when making an estimate/prediction
Inferential
The branch of statistics that uses sample info to make conclusions about a population is called
Inferential statistics
The - estimate states the range within which a population parameter probably lies
Interval
What level of measurement is the Centigrade temperature scale?
Interval
The scale used to measure a quantitative variable is either
Interval or Ratio
What measurement scale is used to measure unemployment?
Interval or ratio
The size of the sampling error is
Inversely related to the sample size (the larger the sample size, the smaller the sampling error)
The probability of rolling a 3 or 2 on a single die is an example of
Mutually Exclusive Events
To apply the special rule of addition, the events must be
Mutually exclusive
When the special rule of addition is used, the events must be
Mutually exclusive
People indicate their political party affiliation as Democrat, Republican or Independent. This data is what type of measurement?
Nominal
The lowest level of measurement is called
Nominal
There are 4 levels of measurement
Nominal, Ordinal, Interval & Ratio
The major advantage of ordinal data over nominal data is that it allows for
Order or ranking
Consumers rated a new DVD played as outstanding, very good, fair or poor. What level of measurement is this?
Ordinal
Respondents were asked, "Do you now earn more than or less than you did five years ago?" What is this level of measurement?
Ordinal
The result of a particular experiment is called a(n)
Outcome
The joint probability of two events, A and B, that are not dependent is computed as
P(A and B) = P(A) P(B|A)
A - chart is useful for displaying the relative frequency distribution for a nominal variable
Pie or Bar
A sample mean is a ___ of the population mean
Point estimate
A point estimate is a single value used to estimate a
Population parameter
An interval estimate is a range of values used to estimate
Population parameter
The items or individuals of the population are arranged in a file drawer alphabetically by date received. A random starting point is selected and then every kth member of the population is selected for the sample. This sampling method is called
Systematic random sampling
Sampling a population is often necessary because
The cost of studying all the items in the population is prohibitive.
An important similarity between uniform and normal probability distributions is
The mean and median are equal
If the size of a sample equals the size of the population, the sample error is
Zero
The sum of the deviations from the mean for the set of numbers 4, 9 and 5 will equal
Zero
The mean of a binomial distribution is the product of
n and π
