Probability

• What is the formula to work out the probability (a AND b happens)

  Pr (A and B) = Pr (A) x Pr (B)
• What is the formula to work out the probability (a OR b happens)

  Pr (A or B) = Pr (A) + Pr (B)
• When can the formula Pr (A or B) = Pr (A) + Pr (B) be used?

  Only for mutually exclusive events
• List 2 examples of mutually exclusive events
• When can the formula Pr (A+B happens) = Pr (A) x Pr (B) be used?

  Only works for independent events
• List 2 non-mutually exclusive events
• List 2 examples for independent events
• List 2 examples of dependant events
• Can the formula Pr (A or B) = Pr (A) + Pr (B) be used for anything?

  No, only for mutually exclusive events
• Can the formula Pr (A + B happens) = Pr (A) x Pr (B) be used anytime?

  No, only for independent events
• Sajid and Kate go to the drinks machine. They buy a drink each. The drinks machine has cola, lemonade, and orange.

  A)List all the permutations of drinks they could buy. (C = cola, O = orange, L = lemonade)

  B)What is the fraction of them both getting cola, buying one cola and one orange, and at least buying one cola

  A)CC, CO, CL, OC, OO, OL, LC, LO, LL

  B)1/9, 2/9, 5/9
• Make a list of al the possible ways of tossing three coins

  What is the fraction of...

  A)getting 3 tails

  B)2 tails and 1 head

  C) at least 1 head

  D) no tails

  A)1/8

  B)3/8

  C)7/8

  D)1/8
• An even with a probability of 1 ________ occurs (choose between "will never", "is unlikely to", "is equally likely to", or "is certain to".)

  is certain to
• An even with a probability of 0 ________ occurs (choose between "will never", "is unlikely to", "is equally likely to", or "is certain to".)

  will never
• An even with a probability of 0.1 ________ occurs (choose between "will never", "is unlikely to", "is equally likely to", or "is certain to".)

  is unlikely to
• An even with a probability of 0.7 ________ occurs (choose between "will never", "is unlikely to", "is equally likely to", or "is certain to".)


  is likely to
• Give an event of your own for each of these possibilities.

  A)Likely to happen

  B) Will never happen

  C)Is unlikely to happen

  D)Is equally likely to happen

  E) Is certain to happen
• A letter is chosen at random from the word VACATION. What is the probability of choosing:

  A)The letter a? (Fraction)

  B)A letter that is not in the word ACTION? (Percentage)

  A)1/4

  B)12.5%
• If the probability of me getting president is 100%, find the probability that I will not get it.

  IMPOSSIBLE
• What are the four suits in a deck of cards?

  Hearts, diamond, clubs, spades
• Each suit has 13 cards:

  Ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, Jack, Queen, and King
• Mr.Knight said he will not include Joker when he is asking a question about the deck of cards.
• If you roll a fair six-sided die, what is the probability of rolling a 3? (Fraction)

  1/6
• You have a bag with 5 red marbles and 3 blue marbles. What is the probability of randomly selecting a red marble? (Percentage)

  62.5%
• A standard deck of playing cards has 52 cards. What is the probability of drawing a spade from a standard deck of cards? (Decimal)

  0.25
• If you spin a spinner divided into 8 equal sections numbered 1 through 8, what is the probability of landing on an even number? (Percentage)

  50%
• If you flip a fair coin twice, what is the probability of getting heads both times? (Fraction)

  1/4
• In a standard deck of 52 cards, what is the probability of drawing a face card (jack, queen, or king) from a shuffled deck without replacement? (Fraction)

  11/221
• A bag contains 8 red balls, 4 blue balls, and 3 green balls. If you draw two balls without replacement, what is the probability of drawing a red ball first and then a blue ball? (Percentage rounded to 2DP)

  15.24%
• If you roll two fair six-sided dice, what is the probability that the sum of the numbers rolled is 7? (Fraction)

  1/6
• In a class of 30 students, 18 play basketball, 12 play soccer, and 6 play both sports. If a student is selected at random, what is the probability that the student plays basketball but not soccer? (Percentage)

  40%
• Two fair coins are tossed simultaneously. What is the probability of getting at least one head? (Percentage)

  75%
• In a game, a player can either roll an even number on a fair six-sided die or roll an odd number. Are these events mutually exclusive?

  Yes
• Suppose you have a bag with 5 red balls and 3 blue balls. You randomly select one ball from the bag, record its color, and then put it back into the bag before selecting another ball. What is the probability of selecting a red ball on the first draw and then selecting another red ball on the second draw? (Fraction)

  25/64
• In a bag, there are 4 red marbles and 2 blue marbles. Two marbles are drawn consecutively without replacement. What is the probability that the first marble drawn is red and the second marble drawn is also red? (Percentage)

  40%