Exam 4: Basic Probability

A company has 2 machines that produce widgets.An older machine produces 23% defective widgets,while the new machine produces only 8% defective widgets.In addition,the new machine produces 3 times as many widgets as the older machine does.Given a randomly chosen widget was tested and found to be defective,what is the probability it was produced by the new machine?

TABLE 4-1 Mothers Against Drunk Driving is a very visible group whose main focus is to educate the public about the harm caused by drunk drivers.A study was recently done that emphasized the problem we all face with drinking and driving.Four hundred accidents that occurred on a Saturday night were analyzed.Two items noted were the number of vehicles involved and whether alcohol played a role in the accident.The numbers are shown below: -Referring to Table 4-1,what proportion of accidents involved more than one vehicle?

The employees of a company were surveyed on questions regarding their educational background (college degree or no college degree)and marital status (single or married).Of the 600 employees,400 had college degrees,100 were single,and 60 were single college graduates.The probability that an employee of the company does not have a college degree is

TABLE 4-11 A sample of 300 adults is selected.The contingency table below shows their registration status and their preferred source of information on current events. -Referring to Table 4-11,if a randomly selected adult is a registered voter,what is the probability that he/she prefers to get his/her current information from the newspapers?

TABLE 4-10 Are whites more likely to claim bias? It was found that 60% of the workers were white,30% were black and 10% are other races.Given that a worker was white,the probability that the worker had claimed bias was 30%.Given that a worker was black,the probability that the worker had claimed bias was 40%.Given that a worker was other race,the probability that the worker had claimed bias was 0%. -Referring to Table 4-10,what is the probability that a randomly selected worker had not claimed bias?

TABLE 4-8 According to the record of the registrar's office at a state university,35% of the students are freshman,25% are sophomore,16% are junior and the rest are senior.Among the freshmen,sophomores,juniors and seniors,the portion of students who live in the dormitory are,respectively,80%,60%,30% and 20%. -Referring to Table 4-8,if a randomly selected student lives in the dormitory,what is the probability that the student is not a freshman?

TABLE 4-8 According to the record of the registrar's office at a state university,35% of the students are freshman,25% are sophomore,16% are junior and the rest are senior.Among the freshmen,sophomores,juniors and seniors,the portion of students who live in the dormitory are,respectively,80%,60%,30% and 20%. -Referring to Table 4-8,if a randomly selected student does not live in the dormitory,what is the probability that the student is a junior or a senior?

TABLE 4-12 Jake woke up late in the morning on the day that he has to go to school to take an important test.He can either take the shuttle bus which is usually running late 20% of the time or ride his unreliable motorcycle which breaks down 40% of the time.He decides to toss a fair coin to make his choice. -Referring to Table 4-12,if Jake,in fact,gets to the test on time,what is the probability that he rode his bike?

The probability that a new advertising campaign will increase sales is assessed as being 0.80.The probability that the cost of developing the new ad campaign can be kept within the original budget allocation is 0.40.Assuming that the two events are independent,the probability that neither the cost is kept within budget nor the campaign will increase sales is

If events A and B are mutually exclusive and collectively exhaustive,what is the probability that event A occurs?

TABLE 4-2 An alcohol awareness task force at a Big-Ten university sampled 200 students after the midterm to ask them whether they went bar hopping the weekend before the midterm or spent the weekend studying,and whether they did well or poorly on the midterm.The following result was obtained. -Referring to Table 4-2,the events "Did Well on Midterm" and "Studying for Exam" are