Math 110 Finite Math Exam 2 Prof. Brick
section 51 Summer ’03
Do the problems in order in your bluebook. Show your work.
1. State the definition of “Aand Bare mutually exclusive events”. Be concise.
2. Your weekly sales commission varies. Twenty percent of the time it is $400. Forty
percent of the time it is $30. And the rest of the time it is $5. Find your expected
commission.
3. You are dealt 3 cards. Find the probability of getting all cards of the same suit but not
all picture cards (picture cards are jacks, queens and kings).
4. A coin is flipped four times. Let Bbe the event that you get heads more often than
tails and Ais the event that your first flip is heads. Find P(A|B), indicating the sample
space used.
5. In the Math Lotto, you pick 5 numbers from 1 thru 40. Getting all five numbers right
wins the grand prize (free math classes for the rest of your life). Getting exactly four
numbers right wins second prize (a bag of boring dirty old hundred dollar bills). Find the
probability of winning second prize.
6. PeeCee computer company has three factories, one in Erehwon making 40% of their
computers, a second in Podunk making 35% of their computers, and the third in Atlantis
making the rest. 2.5% of the Erehwon computers are defective, 4.5% of the Podunk
computers are defective and 3.25% of the Atlantis computers are defective. Find the
probability that a randomly selected PeeCee computer is defective.
7. You roll a pair of dice and win $3 for a nine or a ten, win $100 for an eleven or a twelve,
and lose $1 otherwise. Find the expected value of the game to you as a player.
8. You flip a coin 4 times. Determine whether the events “the first two flips are heads”
and “three of the flips are heads” are independent or dependent.
9. You are dealt 2 cards from a deck of cards. Find the probability that the second one is
a heart. (Hint: the first card is either a heart or not a heart.)
