Introduction To Statistics And Data Analysis
6th Edition
ISBN: 9781337794503
Author: PECK
Publisher: Cengage
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Textbook Question
Chapter 7, Problem 13CRE
Suppose that a new Internet company Mumble.com requires all employees to take a drug test. Mumble.com can afford only the inexpensive drug test—the one with a 5% false-positive rate and a 10% false-negative rate. (That means that 5% of those who are not using drugs will incorrectly test positive and that 10% of those who are actually using drugs will test negative.) Suppose that 10% of those who work for Mumble.com are using the drugs for which Mumble is checking. (Hint: It may be helpful to draw a tree diagram to answer the questions that follow.)
- a. If one employee is chosen at random, what is the
probability that the employee both uses drugs and tests positive? - b. If one employee is chosen at random, what is the probability that the employee does not use drugs but tests positive anyway?
- c. If one employee is chosen at random, what is the probability that the employee tests positive?
- d. If we know that a randomly chosen employee has tested positive, what is the probability that he or she uses drugs?
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Recent research commissioned by Vodafone suggests that older workers are the happiest employees (BBC News, July 21, 2008). The report documents that 70% of older workers in England feel fulfilled, compared with just 50% of younger workers. A demographer believes that an identical pattern does not exist in Asia. A survey of 120 older workers in Asia finds that 75 feel fulfilled. A similar survey finds that 58% of 210 younger workers feel fulfilled. (You may find it useful to reference the appropriate table: z table or t table)
At the 5% level of significance, test if older workers in Asia feel less fulfilled than their British counterparts.
a-1. Select the null and the alternative hypotheses.
multiple choice 1
H0: p = 0.70; HA: p ≠ 0.70
H0: p ≤ 0.70; HA: p > 0.70
H0: p ≥ 0.70; HA: p < 0.70
a-2. Calculate the sample proportion. (Round your answer to 3 decimal places.)
a-3. Calculate the value of test statistic. (Negative value should be indicated…
Suppose that a new Internet company Mumble.com requires all employees to take a drug test. Mumble.com can afford only the inexpensive drug test—the onewith a 5% false-positive rate and a 10% false-negativerate. (That means that 5% of those who are not usingdrugs will incorrectly test positive and that 10% of thosewho are actually using drugs will test negative.) Supposethat 10% of those who work for Mumble.com are usingthe drugs for which Mumble is checking. (Hint: It maybe helpful to draw a tree diagram to answer the questionsthat follow.)a. If one employee is chosen at random, what is theprobability that the employee both uses drugs and testspositive?b. If one employee is chosen at random, what is theprobability that the employee does not use drugs buttests positive anyway?c. If one employee is chosen at random, what is the probability that the employee tests positive?d. If we know that a randomly chosen employee has testedpositive, what is the probability that he or she usesdrugs?
An entrepreneur owns 20 corporations, each with more than $10 million in assets. The entrepreneur consults the U. S. Internal Revenue Data Book and discovers that the IRS audits 20% of businesses of that size. On average how many of this entrepreneur's corporations do you expect will be audited. You can assume that all 20 corporations are independent.
You do not need any knowledge about the IRS. Use probably and statistics.
Chapter 7 Solutions
Introduction To Statistics And Data Analysis
Ch. 7.1 - State whether each of the following random...Ch. 7.1 - Classify each of the following random variables as...Ch. 7.1 - Starting at a particular time, each car entering...Ch. 7.1 - A point is randomly selected from the interior of...Ch. 7.1 - A point is randomly selected on the surface of a...Ch. 7.1 - Prob. 6ECh. 7.1 - A box contains four slips of paper marked 1, 2, 3,...Ch. 7.2 - Define the random variable x to be the number of...Ch. 7.2 - Using the probability distribution given in the...Ch. 7.2 - Let y denote the number of broken eggs in a...
Ch. 7.2 - Use the probability distribution given in the...Ch. 7.2 - Suppose that fund-raisers at a university call...Ch. 7.2 - Airlines sometimes overbook flights. Suppose that...Ch. 7.2 - Suppose that a computer manufacturer receives...Ch. 7.2 - Simulate the chance experiment described in the...Ch. 7.2 - Of all airline flight requests received by a...Ch. 7.2 - Suppose that 20% of all homeowners in an...Ch. 7.2 - A box contains five slips of paper, marked 1, 1,...Ch. 7.2 - Components coming off an assembly line are either...Ch. 7.2 - When applying for a building permit, a contractor...Ch. 7.2 - A library subscribes to two different weekly news...Ch. 7.3 - Let x denote the lifetime (in thousands of hours)...Ch. 7.3 - Using the density curve for fan lifetime given in...Ch. 7.3 - A particular professor never dismisses class...Ch. 7.3 - Refer to the probability distribution given in the...Ch. 7.3 - The article Probabilistic Risk Assessment of...Ch. 7.3 - Use the density curve of x = distance of actual...Ch. 7.3 - Let x denote the amount of gravel sold (in tons)...Ch. 7.3 - Use the density curve for x = amount of gravel...Ch. 7.3 - Let x be the amount of time (in minutes) that a...Ch. 7.3 - Ref erring to the previous exercise, let x and y...Ch. 7.3 - The density curve for the random variable w (the...Ch. 7.4 - Consider selecting a household in rural Thailand...Ch. 7.4 - Suppose the probability distribution of x, the...Ch. 7.4 - Consider the following probability distribution...Ch. 7.4 - Referring to the previous exercise, use the result...Ch. 7.4 - Exercise 7.8 gave the following probability...Ch. 7.4 - Prob. 38ECh. 7.4 - Prob. 39ECh. 7.4 - Refer to the information given in Exercise 7.39....Ch. 7.4 - Refer to the information given in Exercise 7.39....Ch. 7.4 - Suppose that for a particular computer...Ch. 7.4 - A local television station sells 15-second,...Ch. 7.4 - An author has written a book and submitted it to a...Ch. 7.4 - A grocery store has an express line for customers...Ch. 7.4 - An appliance dealer sells three different models...Ch. 7.4 - To assemble a piece of furniture, a wood peg must...Ch. 7.4 - A multiple-choice exam consists of 50 questions....Ch. 7.4 - Consider a game in which a red die and a blue die...Ch. 7.4 - Consider the random variables xR and xB defined in...Ch. 7.5 - CBS News reported that 4% of adult Americans have...Ch. 7.5 - Flight View surveyed 2600 North American airline...Ch. 7.5 - Refer to the previous exercise, and suppose that...Ch. 7.5 - Twenty-five percent of the customers of a grocery...Ch. 7.5 - Example 7.18 described a study in which a person...Ch. 7.5 - Information Security Buzz provides news for the...Ch. 7.5 - A breeder of show dogs is interested in the number...Ch. 7.5 - Womens Health Magazine surveyed 1187 readers to...Ch. 7.5 - Prob. 60ECh. 7.5 - Suppose that the probability is 0.1 that any given...Ch. 7.5 - Suppose that 30% of all automobiles undergoing an...Ch. 7.5 - Suppose that you will take a multiple-choice exam...Ch. 7.5 - Suppose that 20% of the 10,000 signatures on a...Ch. 7.5 - A city requires that smoke detectors be installed...Ch. 7.5 - Suppose that 90% of all registered California...Ch. 7.5 - Suppose a playlist on a music player consists of...Ch. 7.5 - Sophie is a dog that loves to play catch....Ch. 7.5 - Suppose that 5% of cereal boxes contain a prize...Ch. 7.6 - Determine the following standard normal (z) curve...Ch. 7.6 - Determine the following standard normal (z) curve...Ch. 7.6 - Determine each of the following areas under the...Ch. 7.6 - Determine each of the following areas under the...Ch. 7.6 - Let z denote a random variable that has a standard...Ch. 7.6 - Let z denote a random variable that has a standard...Ch. 7.6 - Let z denote a random variable having a normal...Ch. 7.6 - Let z denote a random variable having a normal...Ch. 7.6 - Let z denote a variable that has a standard normal...Ch. 7.6 - Determine the value z that a. Separates the...Ch. 7.6 - Determine the value of z such that a. z and z...Ch. 7.6 - Because P(z 0.44) = 0.67, 67% of all z values are...Ch. 7.6 - Consider the population of all 1-gallon cans of...Ch. 7.6 - Consider babies born in the normal range of 3743...Ch. 7.6 - Use the information on birth weights for babies...Ch. 7.6 - Emissions of nitrogen oxides, which are major...Ch. 7.6 - The paper referenced in Example 7.30 (Estimating...Ch. 7.6 - The size of the left upper chamber of the heart is...Ch. 7.6 - The paper referenced in the previous exercise also...Ch. 7.6 - The article New York Citys Graffiti-Removal...Ch. 7.6 - A machine that cuts corks for wine bottles...Ch. 7.6 - Refer to the previous exercise. Suppose that there...Ch. 7.6 - Purchases made at small corner stores were studied...Ch. 7.6 - The time that it takes a randomly selected job...Ch. 7.6 - Suppose that the distribution of typing speed in...Ch. 7.6 - Consider the typing speed distribution described...Ch. 7.6 - Consider the typing speed distribution described...Ch. 7.7 - The authors of the paper Development of...Ch. 7.7 - The paper Risk Behavior, Decision Making, and...Ch. 7.7 - Prob. 99ECh. 7.7 - Prob. 100ECh. 7.7 - Macular degeneration is the most common cause of...Ch. 7.7 - The following normal probability plot was...Ch. 7.7 - Consider the following 10 observations on the...Ch. 7.7 - Prob. 104ECh. 7.7 - Prob. 105ECh. 7.7 - Prob. 106ECh. 7.7 - Prob. 107ECh. 7.7 - The figure on the next page appeared in the paper...Ch. 7.8 - Let x denote the IQ of an individual selected at...Ch. 7.8 - Suppose that the distribution of x = the number of...Ch. 7.8 - The number of vehicles leaving a turnpike at a...Ch. 7.8 - Suppose that x has a binomial distribution with n...Ch. 7.8 - Prob. 113ECh. 7.8 - Prob. 114ECh. 7.8 - Prob. 115ECh. 7.8 - Suppose that 70% of the bicycles sold by a certain...Ch. 7.8 - Suppose that 25% of the fire alarms in a large...Ch. 7.8 - Suppose that 65% of all registered voters in a...Ch. 7.8 - Flashlight bulbs manufactured by a certain company...Ch. 7.8 - A company that manufactures mufflers for cars...Ch. 7 - Let x denote the duration of a randomly selected...Ch. 7 - A soft-drink machine dispenses only regular Coke...Ch. 7 - A business has six customer service telephone...Ch. 7 - Prob. 124CRCh. 7 - Refer 10 the probability distribution given in...Ch. 7 - A new batterys voltage may be acceptable (A) or...Ch. 7 - A pizza company advertises that it puts 0.5 pounds...Ch. 7 - Suppose that fuel efficiency for a particular...Ch. 7 - A coin is flipped 25 times. Let x be the number of...Ch. 7 - The probability distribution of x, the number of...Ch. 7 - The amount of time spent by a statistical...Ch. 7 - The lifetime of a certain brand of battery is...Ch. 7 - A machine producing vitamin E capsules operates so...Ch. 7 - The Wall Street Journal (February 15, 1972)...Ch. 7 - The longest run of Ss in the sequence SSFSSSSFFS...Ch. 7 - Four peoplea, b, c, and dare waiting to give...Ch. 7 - Kyle and Lygia are going to play a series of...Ch. 7 - Suppose that your statistics professor tells you...Ch. 7 - Suppose that the pH of soil samples taken from a...Ch. 7 - The lightbulbs used to provide exterior lighting...Ch. 7 - Suppose there are approximately 40,000 travel...Ch. 7 - Prob. 2CRECh. 7 - Prob. 3CRECh. 7 - Prob. 5CRECh. 7 - Prob. 6CRECh. 7 - Two shipping services offer overnight delivery of...Ch. 7 - Prob. 8CRECh. 7 - Prob. 9CRECh. 7 - The Cedar Rapids Gazette (November 20, 1999)...Ch. 7 - Prob. 11CRECh. 7 - The article Men, Women at Odds on Gun Control...Ch. 7 - Suppose that a new Internet company Mumble.com...Ch. 7 - Refer to the previous exercise. Suppose that...Ch. 7 - A chemical supply company currently has in stock...Ch. 7 - Prob. 16CRECh. 7 - An experiment was conducted to investigate whether...Ch. 7 - A machine that produces ball bearings has...Ch. 7 - Consider the variable x = time required for a...Ch. 7 - The accompanying data on x = student-teacher ratio...Ch. 7 - Prob. 21CRE
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