Cisb 241 Exam 1

Consider the chart above. Which of the following statements is most correct?

There is a positive linear relationship between the two variables.

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?

Time-series data

In developing and conducting a survey, what is the purpose of the pre-test phase?

To catch any problems with the questionnaire before it is fully administered

A study of a soda filling machine revealed that the mean fill of a can is 12 ounces with a standard deviation of 0.2 ounces. The probability a can is in the bottom 10% (under filled) if a can weight is what value or less. The following is a graphic representation of the problem.

To find the z-score associated with the left 10% using Excel, =norm.s.inv(.10) = -1.28 rounded to two decimals, To find the x-value associated with the left 10% for a can of soda using Excel, =norm.inv(.10,12,.2) = 11.74 rounded to two decimals, & There is a 10% probability that a randomly selected can of soda will have 11.74 ounces or less.

Which of the following is a reason for constructing a joint frequency distribution? Product Issues by Manufacturing Plant Corrosion Cracked Lens Wiring Sound Rochester, NY 30 62 39 16 Miami, FL 3 22 24 8 Houston, TX 2 6 6 4

To help analyze the relationship between the two variables

A sampling distribution for Xbar is the distribution of all possible sample means that could be computed from the possible samples of a given sample size.

True

A short survey with closed-end questions is likely to have a better response rate than a long survey with open-ended questions.

True

A study of 4000 Dell PC customers listed the age of the customer among other variables. The youngest customer was 14 years old and the oldest customer was 84 years old. If analysts for the company wish to develop a frequency distribution with 7 classes, the smallest value that the class width can be is 10 years.

True

An increase in sample size will tend to result in less sampling error.

True

At the end of the school term, students are asked to rate the course and instructor by indicating on a scale of 1-5 how well they liked the course. The data generated from this question are examples of ordinal data.

True

Based on the empirical rule we can assume that all distributions have approximately 95 percent of the values within +- 2 standard deviations of the mean.

True

Data are considered to be left-skewed when the mean lies to the left of the median on a number line.

True

For a standard normal distribution, the orange shaded area on the graph represents the probability of a value being between +1 and its population mean P(0<z<1) and the next graph represents that of a value being between -1 and its population mean P(-1<z<0). True or false: Since the distance away from the mean is 1 unit away from the mean in both, the probabilities are equal.

True

For the same data, a graph of a relative frequency distribution will look exactly the same as a graph of the frequency distribution.

True

On a survey, the questions pertaining to the background of the respondent (age, gender, etc.) are referred to as demographic questions.

True

One of the things that the Central Limit Theorem tells us is that about half of the sample means will be greater than the population mean and about half will be less.

True

Sampling error is the difference between the sample mean and the population mean.

True

Sometime it is necessary to assign probabilities based on a person's belief that an outcome will occur, this is called subjective probability assessment.

True

Statistics is a discipline that involves tools and techniques used to describe data and draw conclusions.

True

The graph of a discrete random variable looks like a histogram where the probability of each possible outcome is represented by a bar.

True

The interquartile range contains the middle 50 percent of a data set.

True

The mean of a sampling distribution would be equal to the mean of the population from which the sampling distribution is constructed.

True

The only two types of random variables are discrete and continuous random variables.

True

Which of the following questions can NOT be answered using a scatter diagram?

What is the trend over time of each of the 2 variables?

Under what circumstances is it necessary to use the coefficient of variation to compare relative variability between two or more distributions?

When the means of the distributions are not equal

For which data collection method is it most important to have a polished-looking survey form?

Written questionnaire

The following probability distribution has been assessed for the number of accidents that occur in a Midwestern city each day: Accidents Probability 0 0.25 1 0.20 2 0.30 3 0.15 4 0.10 This distribution is an example of:

a discrete probability distribution.

To show how the price of a stock has changed over the last 3 months, the best type of chart to use is:

a line chart

A value computed from a population is called:

a parameter.

The managers at Harris Pizza in Boston have tracked the tips received by their drivers along with the total bill to the customer. An appropriate graph for analyzing the relationship between these two variables is:

a scatter diagram.

If a business manager selected a sample of customers and computed the mean income for this sample of customers, she has computed:

a statistic.

A common rule of thumb for determining how many classes to use when developing a frequency distribution with classes is:

between 5 and 20 classes.

The Biltmore Hotel manager is getting ready to make a presentation that she hopes will justify adding additional staff. As part of the presentation, she has constructed charts and graphs. The general type of statistical analysis she is using is:

descriptive statistics.

The use of charts and graphs is an example of:

descriptive statistics.

A stem and leaf diagram is an alternative to using: Stem-and-Leaf Display Stem unit: 10 18 2 6 6 7 19 0 4 7 8 20 2 6 21 1 1 4 9 22 0 2 3 6 8 8 9 23 2 3 3 6 8 24 0 2 2 2 3 4 6 8 8 9

histogram

Estimation and hypothesis testing are categories of:

inferential statistics.

When sampling from a population, the sample mean will:

likely be different from the population mean.

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:

numerical measures.

When the park ranger at Yellowstone National Park reports the average length of time that visitors spend in the park, he is using:

numerical measures.

When a survey uses the responses strongly disagree, disagree, neutral, agree, strongly agree, this is an example of:

ordinal data.

A population measure, such as the population mean, is called a:

parameter.

Portfolio A of a collection of stocks is considered more risky than portfolio B if

portfolio A has a higher coefficient of variation than portfolio B.

When data are organized into levels, the highest data level is:

ratio level data.

In order to compute the mean and standard deviation, the level of data measurement should be:

ratio or interval.

A common method of probability assessment used in business is an examination of historical data from similar situations. This method is called:

relative frequency of occurrence.

A study was recently done in which 500 people were asked to indicate their preferences for one of three products. The following table shows the breakdown of the responses by gender of the respondents. Product Preference Gender A B C Male 80 20 10 Female 200 70 120 If the people conducting the study wish to assess the probability that product A will be preferred by members of the target population, the method of assessment to be used would most likely be:

relative frequency of occurrence.

One of the advantages that a stem and leaf diagram has over a histogram is:

the detail of the data is preserved.

For ordinal data, ________ is the preferred measure of central location.

the median

A line chart is most appropriate for:

time-series data

The Empirical Rule states that for a bell-shaped distribution, approximately 95 percent of data should lie within

two standard deviations from either side of the mean.

At a sawmill in Oregon, a process improvement team measured the diameters for a sample of 1,500 logs. The following summary statistics were computed: Q1 = 8.7 in. Q2 = 13.5 in. Q3 = 15.4 in in. Given this information, the boundaries on the box in a box and whisker plot are:

8.7 in and 15.4 in.

A study of a soda filling machine revealed that the mean fill of a can is 12 ounces with a standard deviation of 0.2 ounces. We want to find the probability that a can will be more than 12.3 ounces. The following is a graphic representation of the problem.

=norm.dist(12.3,12,0.2,true)= .0668

Which of the following is NOT true of a bar chart?

A bar chart is used for numeric data and shows the shape and distribution of the data.

A study was recently conducted by the regional electric and gas company. Data were collected for three customer categories showing the dollar amount of natural gas and the dollar amount of electricity consumed during the year. Which of the following graphs would most likely be used to display both sets of data together?

Bar chart

A recent study in the restaurant business determined: the mean tips for female waiters per hour of work are $6.78 with a standard deviation of $2.11, which gives a coefficient of variation of 31%. the mean tips per hour for male waiters are $7.86 with a standard deviation of $2.20, which gives a coefficient of variation of 28% Based on this information, which of the following statements do we know to be true?

Based on the coefficient of variation, females have more variation in tips per hour than do males.

In conducting a personal interview, what problem can result if the interviewer is allowed to arbitrarily decide who should be interviewed?

Bias

Which of the following is not true about the basic rules of probability?

It is possible to exceed a probability of 1.

Which of the following data collection methods is most likely to generate the largest nonresponse?

Mail surveys

Which of the following is not considered desirable when constructing a frequency distribution for continuous data? Class Frequency 146-185 4 186-225 16 226-265 33 266-305 26 306-345 21 346-385 9 386-425 1

Open-ended classes

The city counsel has just voted to pass the city's budget for next year. If you were writing a report describing the budget so the citizens could understand how the total tax dollars will be spent, which of the following graphs might be most appropriate?

Pie chart

A histogram is most commonly used to analyze which of the following?

Quantitative data

A car salesman has noted that the probability the dealiership sells a car on an Saturday morning is .25. The probability of the dealership not selling a car on Saturday morning is:

.75

The method of probability assessment that is least likely to be used by business decision makers is:

Classical assessment

The other method to determine probabilities for a standard normal distribution is to use Appendix D Standard Normal Distribution Table on page 764. Which of the following is not true?

If the z-score is negative, the probability is negative.

Which of the following is not a characteristic of the normal distribution?

Equal probabilities at all values of x

A sample can be assumed normally distributed if n ≥ 30.

False

Descriptive statistics allow a decision maker to reach a conclusion about a populations based on a subset from the population.

False

If the z=2.5789, using =norm.s.dist(2.5789,true) will give the exact same answer as using the book Appendix D for z=2.58.

False

In a scatter plot the points should always be connected with a line.

False

Sampling error can be eliminated if the sample size is large enough.

False

Sampling error can be eliminated if the sampling is done properly.

False

The symbol μ μ (Mu) is used to represent the sample mean.

False

Typically, it is possible to include more questions in a phone survey than in a mail survey since it takes less time to complete the survey over the phone.

False

When a variance is calculated for a data set, the resulting value is the same regardless of whether the data set is treated as a population or a sample.

False

When choosing class boundaries for a frequency distribution, classes such as 60-70, 70-80, 80-90 would be acceptable.

False

When the United States conducts a census that counts all people in the country this is an example of using a sample.

False

A large retail company gives an employment screening test to all prospective employees. Franklin Gilman recently took the test and it was reported back to him that his score placed him at the 80th percentile. Therefore:

Franklin scored as high or higher than 80 percent of the people who took the test.

The human resources department at a major high tech company recently conducted an employee satisfaction survey of 100 of its 3,000 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 would be classified as nominal level data?

Gender, marital status, and job title

Some of the most common methods of collecting data include experiments, telephone surveys, mail questionnaires, online surveys, direct observations and personal interviews.

TRue

Which of the following statements is not consistent with the Central Limit Theorem?

The Central Limit Theorem applies without regard to the size of the sample.

If a grouped column chart is made from data and it appears to be normally distributed, then it can be converted to a standard normal distribution. Which of the following is true about the standard normal distribution?

The mean of the standard normal distribution is,The standard deviation of the standard normal distribution is 1, & The formula used to convert a value is z=(x−μ)σ=(x−μ)/σ

Which of the following measures is not affected by extreme values in the data?

The median

A value(x) is converted to a standard normal distribution with a z score = 1.5 and is graphed as follows: Z-Score Plot at 1.5 above the mean. What does this tell you about the value(x)?

The value is 1.5 standard deviations larger than the mean.

A histogram is used to display which of the following characteristics for a quantitative variable?

The shape of the distribution, The approximate center of the data, & The spread in the data

Which of the following is the most frequently used measure of variation?

The standard deviation