Unit 13 Probability 13 Strengthen Calculating probabilities 1 The letters from the word MATHEMATICS are placed in a hat. Q1a hint How many letters a One letter is selected at random. are there in the word? How many possible outcomes are there? b What is the probability of Number of Ms i selecting an M Q1b i hint ____________________ Total number of letters ii selecting a C iii selecting a vowel Q1b iv hint How many letters are not ‘A’? iv not selecting an A? 2 A bag contains 7 blue balls, 5 red balls and 1 green ball. What is a P(blue)? b P(blue or red)? c P(not red)? 3 Cards numbered 1–5 are put in a bag. 1 2 3 4 5 One card is picked at random. Work out a P(odd) b P(even) c P(square number) d P(not square number) Discussion Are all the numbers 1–5 odd or even? Can a number be both odd and even? What is P(even) + P(odd)? 4 The probability of getting a six on a fair dice is _ 16 . Write the probability of not getting a six. 5 The table shows the probabilities of trains arriving early, late or on time. Arrival Probability Early Late 0.1 Q2 hint P(blue) means probability of blue. Q4 hint P(6) 5 16 P(not 6) 5 1 2 3 4 5 6 On time 0.6 Work out the probability of a train arriving late. Q5 hint Early, late or on time are the only possible outcomes. Experimental probability 1 Communication Maddie rolls a dice and records the number of times she gets a 2. Freya does the same with a different dice. Maddie Freya Number of rolls 60 90 Number of 2s 12 30 Q1a hint What is the probability a Write the theoretical probability of rolling a 2. of rolling a 2 on a fair dice? b Write the experimental probability of i Maddie getting a 2 ii Freya getting a 2? c Compare the experimental probabilities with the theoretical probability. Do you think either dice is biased? Explain your answer. Homework, practice and support: Foundation 13 Strengthen 401