91影视

Get rich A survey of $4826$ randomly selected young adults (aged $19$ to $25$) asked, 鈥淲hat do you think are the chances you will have much more than a middle-class income at age $30$?鈥� The two-way table shows the responses.

$14$ Choose a survey respondent at random.

(a) Given that the person selected is male, what鈥檚 the probability that he answered 鈥渁lmost certain鈥�?

(b) If the person selected said 鈥渟ome chance but probably not,鈥� what鈥檚 the probability that the person is female?

A Titanic disaster In $1912$the luxury liner Titanic, on its first voyage across the Atlantic, struck an iceberg and sank. Some passengers got off the ship in lifeboats, but many died. The two-way table gives information about adult passengers who lived and who died, by class of travel. Suppose we choose an adult passenger at random.

(a) Given that the person selected was in first class, what鈥檚 the probability that he or she survived?

(b) If the person selected survived, what鈥檚 the probability that he or she was a third-class passenger?

Get rich Refer to Exercise 63.

(a) Find P(鈥渁 good chance鈥� | female).

(b) Find P(鈥渁 good chance鈥�).

(c) Use your answers to (a) and (b) to determine whether the events 鈥渁 good chance鈥� and 鈥渇emale鈥� are

independent. Explain your reasoning.

A Titanic disaster Refer to Exercise 64.

(a) Find P(survived | second class).

(b) Find P(survived).

(c) Use your answers to (a) and (b) to determine whether the events 鈥渟urvived鈥� and 鈥渟econd class鈥� are independent. Explain your reasoning.

Sampling senators The two-way table describes the members of the U.S. Senate in a recent year. Suppose we select a senator at random. Consider events D: is a democrat, and F: is female.

(a) Find P(D | F). Explain what this value means.

(b) Find P(F | D). Explain what this value means.

Who eats breakfast? The two-way table describes the 595 students who responded to a school survey about eating breakfast. Suppose we select a student at random. Consider events B: eats breakfast regularly, and $M$: is male.

(a) Find $P(B|M)$ Explain what this value means.

(b) Find$P(M|B)$ Explain what this value means.

Sampling senators Refer to Exercise 67. Are events D and F independent? Justify your answer.

Free throws The figure below shows the results of a basketball player shooting several free throws. Explain what this graph says about chance behavior in the short run and long run.

Who eats breakfast? Refer to Exercise 68. Are events B and M independent? Justify your answer.

Foreign-language study Choose a student in grades $9$to $12$at random and ask if he or she is studying a language other than English. Here is the distribution of results:

(a) What鈥檚 the probability that the student is studying a language other than English?

(b) What is the conditional probability that a student is studying Spanish given that he or she is studying some language other than English?