Exam 4: Introduction to Probability

An automobile dealer has kept records on the customers who visited his showroom.Forty percent of the people who visited his dealership were female.Furthermore,his records show that 35% of the females who visited his dealership purchased an automobile,while 20% of the males who visited his dealership purchased an automobile.Let A₁ = the event that the customer is female A₂ = the event that the customer is male a.What is the probability that a customer entering the showroom will buy an automobile? b.A car salesperson has just informed us that he sold a car to a customer.What is the probability that the customer was female?

The addition law is potentially helpful when we are interested in computing the probability of

From a group of seven finalists to a contest,three individuals are to be selected for the first and second and third places.Determine the number of possible selections.

A student has to take 7 more courses before she can graduate.If none of the courses are prerequisites to others,how many groups of three courses can she select for the next semester?

The intersection of two mutually exclusive events

Events A and B are mutually exclusive if their joint probability is

A committee of 4 is to be selected from a group of 12 people.How many possible committees can be selected?

Events that have no sample points in common are

If a six sided die is tossed two times,the probability of obtaining two "4s" in a row is

The counting rule that is used for counting the number of experimental outcomes when n objects are selected from a set of N objects where order of selection is important is called

The sum of the probabilities of two complementary events is

Eight individuals are candidates for positions of president,vice president,and treasurer of an organization.How many possibilities of selections exist?

Forty percent of the students who enroll in a statistics course go to the statistics laboratory on a regular basis.Past data indicates that 65% of those students who use the lab on a regular basis make a grade of A in the course.On the other hand,only 10% of students who do not go to the lab on a regular basis make a grade of A.If a particular student made an A,determine the probability that she or he used the lab on a regular basis.

Which of the following statements is always true?

The probability of an economic decline in the year 2008 is 0.23.There is a probability of 0.64 that we will elect a republican president in the year 2008.If we elect a republican president,there is a 0.35 probability of an economic decline.Let "D" represent the event of an economic decline,and "R" represent the event of election of a Republican president. a.Are "R" and "D" independent events? b.What is the probability of a Republican president and economic decline in the year 2008? c.If we experience an economic decline in the year 2008,what is the probability that there will a Republican president? d.What is the probability of economic decline or a Republican president in the year 2008? Hint: You want to find P(D| R).

If P(A)= 0.45,P(B)= 0.55,and P(A $\cup$ B)= 0.78,then P(A | B)=

Ten individuals are candidates for positions of president,vice president of an organization.How many possibilities of selections exist?

The set of all possible sample points (experimental outcomes)is called

A method of assigning probabilities based upon judgment is referred to as the

The collection of all possible sample points in an experiment is