Exam 4: Basic Probability

True or False: An investment consultant is recommending a certain class of mutual funds to the clienteles based on its exceptionally high probability of gain.It is an ethical practice to explain to the clienteles what the basis of her probability estimate is.

TABLE 4-6 At a Texas college,60% of the students are from the southern part of the state,30% are from the northern part of the state,and the remaining 10% are from out-of-state.All students must take and pass an Entry Level Math (ELM)test.60% of the southerners have passed the ELM,70% of the northerners have passed the ELM,and 90% of the out-of-staters have passed the ELM. -Referring to Table 4-6,if a randomly selected student has passed the ELM,the probability that the student is from out-of-state is ________.

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 3 vehicles were involved,what proportion of accidents involved alcohol?

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 hamburger.The probability that this individual is a child is ________.

TABLE 4-9 A survey conducted by the Segal Company of New York found that in a sample of 189 large companies,40 offered stock options to their board members as part of their noncash compensation packages.For small- to mid-sized companies,43 of the 180 surveyed indicated that they offer stock options as part of their noncash compensation packages to their board members. -Referring to Table 4-9,set up a contingency table.

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 is the probability that a randomly selected student is a freshman who lives in a dormitory?

True or False: Referring to Table 4-4,the two events "preferring water" and "preferring soda" are independent.

According to a survey of American households,the probability that the residents own 2 cars if annual household income is over $50,000 is 80%.Of the households surveyed,60% had incomes over $50,000 and 70% had 2 cars.The probability that annual household income is over $50,000 if the residents of a household do not own 2 cars is

True or False: An investment consultant is recommending a certain class of mutual funds to the clienteles based on its exceptionally high probability of exceptionally high gain.It is an unethical practice to tell the clienteles the probability of a loss in her recommendations.

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 is ________.

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 a child and prefers chicken is ________.

According to a survey of American households,the probability that the residents own 2 cars if annual household income is over $50,000 is 80%.Of the households surveyed,60% had incomes over $50,000 and 70% had 2 cars.The probability that the residents do not own 2 cars if annual household income is not over $50,000 is

If P(A and B) = 1, then A and B must be collectively exhaustive.

TABLE 4-6 At a Texas college,60% of the students are from the southern part of the state,30% are from the northern part of the state,and the remaining 10% are from out-of-state.All students must take and pass an Entry Level Math (ELM)test.60% of the southerners have passed the ELM,70% of the northerners have passed the ELM,and 90% of the out-of-staters have passed the ELM. -Referring to Table 4-6,if a randomly selected student has not passed the ELM,the probability that the student is not from northern Texas is ________.

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,suppose a randomly selected patron is a female.Then the probability that the patron prefers water is ________.

If two events are collectively exhaustive,what is the probability that both occur at the same time?

The closing price of a company's stock tomorrow can be lower,higher or the same as today's closing price.After evaluating all the information available on the company's fundamentals and the economic environment,an analyst has determined that the probability that tomorrow's closing price will be higher than today's is determined to be 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 not a registered voter or does not prefer to get his/her current information from the internet?

True or False: If P(A and B)= 0,then A and B must be mutually exclusive.

TABLE 4-7 The next state lottery will have the following payoffs possible with their associated probabilities. You buy a single ticket. -Referring to Table 4-7,the probability that you win at least $100.00 is ________.