Chapter 2 Test Review

The expected (mean) life of a particular type of light bulb is 1,000 hours with a standard deviation of 50 hours. The life of this bulb is normally distributed. What is the probability that a randomly selected bulb would last longer than 1150 hours?

0.0013

Which of the following is a legitimate probability value?

0.28

The expected (mean) life of a particular type of light bulb is 1,000 hours with a standard deviation of 50 hours. The life of this bulb is normally distributed. What is the probability that a randomly selected bulb would last fewer than 1100 hours?w

0.9772

The mean life of a particular brand of light bulb is 1200 hours and the standard deviation is 50 hours. It can be concluded that at least 89% of this brand of bulbs will last between _______.

1050 and 1350 hours

The mean life of a particular brand of light bulb is 1200 hours and the standard deviation is 50 hours. We can conclude that at least 75% of this brand of bulbs will last between _______.

1100 and 1300 hours

The mean life of a particular brand of light bulb is 1200 hours and the standard deviation is 75 hours. Tests show that the life of the bulb is approximately normally distributed. It can be concluded that approximately 68% of the bulbs will last between _______.

1125 and 1275 hours

Suppose the total time to fill a routine prescription at a local pharmacy is 35 minutes based on the time the physician places the order to the time it is dispensed. Assume the standard deviation is 11 minutes and the z score is -1.3. What is x?

14.3

The mean of a normal probability distribution is 400 pounds. The standard deviation is 10 pounds. What is the are (P) between the mean and 395 pounds?

19.15%

Jessica Salas, president of Salas Products, is reviewing the warranty policy for her company's new model of automobile batteries. Life tests performed on a sample of 100 batteries indicated: (1) an average life of 75 months, (2) a standard deviation of 5 months, and (3) a bell shaped battery life distribution. What percentage of the batteries will fail within the first 65 months of use?

2.5%

A sample of 117 records of the selling price in dollars of homes from Feb 15 to Apr 30, 2013 was taken from the files maintained by the Albuquerque Board of Realtors. The following are summary statistics for the selling prices. Variable N Mean Minimum Q1 Median Q3 Maximum Prices 117 106270 54000 77650 96000 121750 215000 From this we can conclude that,

25% of the selling price of homes is at least $121750

The average starting salary for graduates at a university is $33,000 with a standard deviation of $2,000. If a histogram of the data shows that it takes on a mound shape, the empirical rule says that approximately 68% of the graduates would have a starting salary between _______.

27,000 and 39,000

The average starting salary for graduates at a university is $33,000 with a standard deviation of $2,000. If a histogram of the data shows that it takes on a mound shape, the empirical rule says that approximately 95% of the graduates would have a starting salary between _______.

27,000 and 39,000

A commuter travels many miles to work each morning. She has timed this trip 5 times during the last month. The time (in minutes) required to make this trip was 38, 33, 36, 47, and 41. What is the variance for this sample data?

28.5

Liz Chapa manages a portfolio of 250 common stocks. Her staff compiled the following performance statistics for two new stocks. Rate of Return Stock Mean Standard Deviation Salas Products, Inc. 15% 5% Hot Boards, Inc. 20% 5% The coefficient of variation for Salas Products, Inc. is __________.

33%

Suppose the total time to fill a routine prescription at a local pharmacy is 35 minutes based on the time the physician places the order to the time it is dispensed. Assume the standard deviation is 11 minutes and the z score is 0. What is x?

35.0

A sample was taken of the salaries of four employees from a large company. The following are their salaries (in thousands of dollars) for this year: 33, 36, 41, and 47. The variance of their salaries is approximately

37.58

The expected (mean) life of a particular type of light bulb is 1,000 hours with a standard deviation of 50 hours. The life of this bulb is normally distributed. What is the probability that a randomly selected bulb would last fewer than 940 hours?

395.0

A commuter travels many miles to work each morning. She has timed this trip 5 times during the last month. The time (in minutes) required to make this trip was 38, 33, 36, 47, and 41. What is the standard deviation for this sample data?

5.34

Which of the following is not a legitimate probability value?

5/4

In its Industry Norms and Key Business Ratios, Dun & Bradstreet reported that Q1, Q2, and Q3 for 2,037 gasoline service stations' sales to inventory ratios were 20.8, 33.4, and 53.8, respectively. From this we can conclude that ____________.

50% of these service stations had sales to inventory ratios of 33.4 or less

Jessica Salas, president of Salas Products, is reviewing the warranty policy for her company's new model of automobile batteries. Life tests performed on a sample of 100 batteries indicated: (1) an average life of 75 months, (2) a standard deviation of 5 months, and (3) a bell shaped battery life distribution. Approximately 99.7% of the batteries will last between ________________.

60 and 90 months

Jessica Salas, president of Salas Products, is reviewing the warranty policy for her company's new model of automobile batteries. Life tests performed on a sample of 100 batteries indicated: (1) an average life of 75 months, (2) a standard deviation of 5 months, and (3) a bell shaped battery life distribution. Approximately 95% of the batteries will last between ________________.

65 and 85 months

Jessica Salas, president of Salas Products, is reviewing the warranty policy for her company's new model of automobile batteries. Life tests performed on a sample of 100 batteries indicated: (1) an average life of 75 months, (2) a standard deviation of 5 months, and (3) a bell shaped battery life distribution. Approximately 68% of the batteries will last between ________________.

70 and 80 months

Suppose the total time to fill a routine prescription at a local pharmacy is 35 minutes based on the time the physician places the order to the time it is dispensed. Assume the standard deviation is 11 minutes.. A z score was calculated for a number, and the z score is 3.4. What is x?

72.4

The empirical rule says that approximately what percentage of the values would be within 2 standard deviations of the mean in a bell shaped set of data?

95%

A box and whisker plot is determined from the mean, the smallest and the largest values, and the lower and upper quartile.

False

A nonzero value of the skewness indicates asymmetry of the distribution of the data.

False

An event that cannot be broken down into other events is called a certainty outcome

False

Assigning probabilities to uncertain events based on one's beliefs or intuitions is called classical method

False

In a standard normal distribution, if the area under curve to the right of a z-value is 0.10, then the area to the left of the same z-value is -0.10.

False

Kurtosis is a measure of the association between two numerical variables.

False

The area under the standard normal distribution between 0 and 2 is twice the area between 0 and 1.

False

The method of assigning probabilities to uncertain outcomes based on laws and rules is called the relative frequency method.

False

What is the probability to get the right answers for the exam 2 when you ask to the classmate?

Should not ask anybody (against the honor code)

Karen Merlott, VP for Strategic Planning at a recruitment firm, recently conducts a survey to determine customer satisfaction with job placement. She distributed the survey to 45 of the most recently placed executives. Two items on a survey questionnaire them to rate the importance of "initial interview process" and "satisfaction of final job placement" on a scale of 1 to 10 (with 1 meaning "not important" and 10 meaning "highly important"). Her staff assembled the following statistics on these two items. Initial Interview Process Satisfaction of Final Job Placement Mean 8.5 7.5 Median 9 8.5 Mode 9.0 9 Standard Deviation 1.0 1.5 What can Karen conclude from these statistics?

The Satisfaction of Final Job Placement distribution is negatively skewed

David Desreumaux, VP of Human Resources of American First Banks (AFB), is reviewing the employee training programs of AFB banks. His staff compiled the following table of regional statistics on teller training hours. Southeast Region Southwest Region Mean 20 28 Median 20 20 Mode 20 21 Standard Deviation 5 7 What can David conclude from these statistics?

The Southeast distribution is symmetrical

A z-score is the number of standard deviations that a value of a random variable is above or below the mean.

True

An outlier of a data set is determined from the lower and upper quartile

True

Assigning probabilities by dividing the number of ways that an event can occur by the total number of possible outcomes in an experiment is called the classical method

True

Computations of the variance and standard deviation using grouped data are potentially only approximation of the actual variance and standard deviation.

True

If the mean of a distribution is greater than the median, then the distribution is positively skewed.

True

If the median of a distribution is greater than mean, then the distribution is skewed to the left.

True

Inferring the value of a population parameter from the statistic on a random sample drawn from the population is an inferential process under uncertainty.

True

The area under the standard normal distribution between -1 and 1 is twice the area between 0 and 1.

True

Which of the following statements is not true regarding probabilities

probabilities are subjective measures with limited value in business.

The number of standard deviations that a value (x) is above or below the mean is the _________________.

z score

Probability is used to develop knowledge of the fundamental mathematical tools for quantitatively assessing risk.

True

An experiment is a process that produces outcomes

True