ECON 3818 CH 12

A student is chosen at random from a statistics class. Which of the following events are disjoint? A. Event 𝐴 is that the student is a junior. Event 𝐵 is that the student is a senior. B. Event 𝐴 is that the student is at least 5'8" tall. Event 𝐵 is that the student weighs at least 160 pounds. C. Event 𝐴 is that the student is a psychology major. Event 𝐵 is that the student is a statistics major.

A

Students at University X must be in one of the following class ranks: freshman, sophomore, junior, or senior. At University X, 35% of the students are freshman and 30% are sophomores. If a student is selected at random, the probability that he or she is either a junior or a senior is: A. 35%. B. 65%. C. 70%.

A

A refrigerator contains 6 apples, 5 oranges, 10 bananas, 3 pears, 7 peaches, 11 plums, and 2 mangos. Imagine you stick your hand into the refrigerator and pull out a piece of fruit at random. What is the sample space for your action? A. 𝑆={6 apples, 5 oranges, 10 bananas, 3 pears, 7 peaches, 11 plums, 2 mangos} B. 𝑆={apple, orange, banana, pear, peach, plum, mango} C. 𝑆={6, 5, 10, 3, 7, 11, 2}

B

The probability distribution of a random variable is: A. the degree to which the variable's possible values are spread out. B. the possible values of the random variable and the frequency with which the variable takes each value. C. the possible values of the random variable.

B

I select two cards from a standard deck of 52 cards and observe the color of each (26 cards in the deck are red and 26 are black). Which of the following is an appropriate sample space 𝑆 for the possible outcomes? A. 𝑆={0, 1, 2} B. 𝑆={(red, red), (red, black), (black, red), (black, black)} C. 𝑆={red, black}

B.

A refrigerator contains 6 apples, 5 oranges, 10 bananas, 3 pears, 7 peaches, 11 plums, and 2 mangos. Imagine you stick your hand into the refrigerator and pull out a piece of fruit at random. What is the chance you don't get an apple? A. 10/44 B. 6/44 C. 38/44

C

Suppose there are three cards in a deck: one marked with a "1,"one marked with a "2,"and one marked with a "5." You draw two cards at random, without replacement from the deck of three cards. The sample space 𝑆={(1,2), (2,1),(1,5),(5,1),(2,5),(5,2)} consists of these six equally likely outcomes. Let 𝑋 be the total of the two cards drawn. Which of the following is the correct set of probabilities for 𝑋 ? A. 𝑋 3 6 7 𝑃 3/16 6/16 7/16 B. 𝑋 1 2 5 𝑃 1/3 1/3 1/3 C. 𝑋 3 6 7 𝑃 1/3 1/3 1/3

C

Personal probabilities are not important since they are based on personal judgment. true false

FALSE