23 a M1 3 M1 for good use of diagram such as two way table to H P(1, 1) = A1 support explanation A1 cao 100 ÷ 36 = 2.7 He can expect to win one in 36 so should expect to have 36 goes to win at least b B1 B1 for correct interpretation of 36 outcomes, of which once. only one wins If he has 100 goes, then he can expect 3 c wins. B1 B1 for division, rounding and correct interpretation in context 4 24 P(BB) = × = M1 3 M1 for multiplication of × and subtraction from 1 H P(RB) = 1 (P(BB) + P(RR)) A1 A1 for use of technical notation and possible use of tree – = 1 ( + ) diagram to aid explanation – = as required. 2 25 a M1 3 M1 for correct construction of probability tree diagram H B1 B1 for probabilities and events identified clearly 0.2 b P(PP) = 0.4 x 0.5 = 0.2 A1 A1 cao 3
23 a b c 100 ÷ 36 = 2.7 P(1, 1) = He can expect to win one in 36 so should expect to have 36 goes to win at least once. If he has 100 goes, then he can expect 3 wins. M1 A1 B1 B1 3 M1 for good use of diagram such as two way table to support explanation A1 cao B1 for correct interpretation of 36 outcomes, of which only one wins B1 for division, rounding and correct interpretation in context H 4 24 P(BB) = × = P(RB) = 1 – (P(BB) + P(RR)) = 1 – ( + ) = as required. M1 A1 3 M1 for multiplication of × and subtraction from 1 A1 for use of technical notation and possible use of tree diagram to aid explanation H 2 25 a b P(PP) = 0.4 x 0.5 = 0.2 0.2 M1 B1 A1 3 M1 for correct construction of probability tree diagram B1 for probabilities and events identified clearly A1 cao H 3
Foundation_Skills_Probability%20MarkScheme_AQA.docx