Exam 4: Basic Probability

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,what is the probability that a randomly selected student who went bar hopping did well on the midterm?

TABLE 4-3 A survey is taken among customers of a fast-food restaurant to determine preference for hamburger or chicken.Of 200 respondents selected,75 were children and 125 were adults.120 preferred hamburger and 80 preferred chicken.55 of the children preferred hamburger. -Referring to Table 4-3,the probability that a randomly selected individual is an adult or a child is ________.

Suppose A and B are events where P(A)= 0.4,P(B)= 0.5,and P(A and B)= 0.1.Then P(B|A)= ________.

TABLE 4-4 Suppose that patrons of a restaurant were asked whether they preferred water or whether they preferred soda.70% said that they preferred water.60% of the patrons were male.80% of the males preferred water. -Referring to Table 4-4,the probability that a randomly selected patron is a female who prefers water is ________.

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 took the bus?

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,what is the probability that a randomly selected student did well on the midterm and also went bar hopping the weekend before the midterm?

If either event A or event B must occur,then events A and B are said to be

The closing price of a company's stock tomorrow can be lower,higher or the same as today's closing price.Based on the closing price of the stock collected over the last month,25% of the days the closing price was higher than previous day's closing price,45% was lower than previous day's and 30% was the same as previous day's.Based on this information,the probability that tomorrow's closing price will be higher than today's is 25%.This is an example of using which of the following probability approaches?

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 an adult is selected at random,what is the probability that he/she is a registered voter who does not prefer to get his/her current information from the internet?

Suppose A and B are events where P(A)= 0.4,P(B)= 0.5,and P(A and B)= 0.1.Then P(A|B)= ________.

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,given that multiple vehicles were involved,what proportion of accidents involved alcohol?

The collection of all possible events is called

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,if a randomly selected worker had not claimed bias,what is the probability that the worker is white?

Selection of raffle tickets from a large bowl is an example of

True or False: If P(A and B)= 1,then A and B must be mutually exclusive.

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 an adult is selected at random,what is the probability that he/she is a registered voter or prefers to get his/her current information from radio?

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,what percentage of the students do not live in a dormitory?

TABLE 4-3 A survey is taken among customers of a fast-food restaurant to determine preference for hamburger or chicken.Of 200 respondents selected,75 were children and 125 were adults.120 preferred hamburger and 80 preferred chicken.55 of the children preferred hamburger. -Referring to Table 4-3,assume we know that a person prefers chicken.The probability that this individual is an adult is ________.

If two events are mutually exclusive,what is the probability that one or the other occurs?

You know that the probability of a randomly selected student will cheat on an exam is 1%.You also know that the probability of a randomly selected student will cheat on an exam knowing that his/her fellow classmate is cheating on the exam is also 1%.Which of the following is true about the event of "the randomly selected student cheating on an exam" and "his/her classmate is cheating on the exam"?