Probability Learning Objective: To be able to understand probability and measure the probability of an event not happening GRADE C YOU MUST Be able to know how to work a probability scale Some should be able to work out probabilities in different situation Some could be able to use experimental probability

The probability of an event not occurring The probability of a factory component being faulty is What is the probability of a randomly chosen component not being faulty? P(not faulty) = 1 – 0.03 =0.97 The probability of pulling a picture card out of a full deck of cards is. What is the probability of not pulling out a picture card? 3 13 P(not a picture card) = 1 – =

Calculating probability If the outcomes of an event are equally likely then we can calculate the probability using the formula: Probability of an event = Number of successful outcomes Total number of possible outcomes For example, a bag contains 1 yellow, 3 green, 4 blue and 2 red marbles. What is the probability of pulling a green marble from the bag without looking? P(green) = 3 10 or 0.3 or 30%

Calculating probability – IN your books calculate A fair dice is thrown. What is the probability of getting a)a 2? b)a multiple of 3? c)an odd number? d)a prime number? e)a number bigger than 6? f)an integer? d) P(a prime number) = 3 6 e) P(a number bigger than 6) = f) P(an integer) = 6 6 = 1 = Don’t write 0 6

The probability of an event not occurring If the probability of an event occurring is p then the probability of it not occurring is 1 – p. The following spinner is spun once: What is the probability of it landing on the yellow sector? P(yellow) = 1 4 What is the probability of it not landing on the yellow sector? P(not yellow) = 3 4

The probability of an event not occurring The probability of a factory component being faulty is What is the probability of a randomly chosen component not being faulty? P(not faulty) = 1 – 0.03 =0.97 The probability of pulling a picture card out of a full deck of cards is. What is the probability of not pulling out a picture card? 3 13 P(not a picture card) = 1 – =

Summary Probability of an event = Number of successful outcomes Total number of possible outcomes Relative Frequency of = An event (Experimental Prob ) Frequency of the event Total Number Trials As the number of trials or experiments increases, the value of the experimental Probability gets closer to the true theoretical probability

Class work Text book at the back! GCSE Higher Edexcel Books Pg 440 Exercise 19a Extension GCSE Foundation Edexcel Books PG 423 Exam Questions 1-15