Functional Question Higher (Statistics 11) For the week beginning ….

At a school Summer Fair a stall has two wheels as shown below. Players spin both wheels. When they stop, straps at the top of the wheels indicate the numbers scored. In the example above the total score is = 12 (a) Write down all the possible combinations that will give a total score of 12 (1) (b) Show that the probability of a total score of 16 is (c) This table shows the possible total scores and their probabilities. Players pay 10p to spin the wheels each time. They get back, in pence, the total score on both wheels. What is the probability that a player would make a profit of 11p or more after two spins of the wheels? (4) (Total 7 marks)

(a) ((4, 8)) (5, 7), (6, 6), (7, 5), (8, 4) Allow repeat of (6, 6) B1 - Marks awarded independent of method (b) P(8) =

Common Mistakes – what did the examiners say? Part (a) was well done with few errors. Repeats of 6, 6 were allowed. Part (b) was less well done with candidates often just writing down 1/8 × 1/8 = 1/64 with no explanation to justify this. Part (c) was not well done. Few scored full marks. Common errors amongst those that did gain some credit on the question were to consider only and or just and Probabilities were often added rather than multiplied. Many candidates did not realise that two goes would cost 20p so calculated all the possibilities above 11p with little success.