Tail. Tail. Head. Tail. Head. Head. Tree diagrams (foundation) 2 nd throw. 1 st throw. P (tail and tail) = P (head and tail) or a tail.

Transcription

1 When you flip a coin, you might either get a head or a tail. The probability of getting a tail is one chance out of the two possible outcomes. So P (tail) = Complete the tree diagram showing the coin being flipped twice. 2 nd throw st throw 2 Tail 2 Tail Head P (tail and tail) = 2 2 Tail P (head and tail) 2 Head Head Page of

2 Rule : When the word and is used in probability, it means to multiply the probabilities. Rule 2: When the word or is used in probability, it means to add the probabilities. Using your tree diagram: a. What is the probability that you throw two TAILS? b. What is the probability that you throw a TAIL and a HEAD in that order? c. What is the probability that you throw a TAIL and a HEAD in any order? Page 2 of

3 Draw a tree diagram showing the probability of throwing a when a dice is rolled twice. st roll 2 nd roll Use the tree diagram to answer: a. What is the probability that you roll a and a?... b. What is the probability that you throw no threes?... c. What is the probability that you throw exactly one in any order?... d. What is the probability that you throw at least one? Page of

4 . A bag contains 7 blue counters and red counters. A counter is taken out at random, the colour noted and put back into the bag. Another counter is then taken out and the colour noted. 2. The probability that Peter eats breakfast is 0.4 a. What is the probability that he doesn t eat breakfast? b. Draw a tree diagram and calculate: i. The probability that he eats breakfast 2 days in a row a. 2 red counters are chosen b. A blue and a red counter in any order are chosen ii. The probability that he eats breakfast at least once in two days. Louise has a fruit juice and an apple almost every day. Complete the tree diagram: 0.8 Juice juice 0.7 Crisps crisps Challenge A bag contains 7 blue counters and red counters. A counter is taken out at random and not replaced. Another counter is then taken out and the colour noted. a. 2 red counters are chosen b. A blue and a red counter in any order are chosen What is the probability that she not have juice or crisps? Page 4 of

5 Solutions P(TAIL and TAIL) = 2 x 2 = 4 P(TAIL and HEAD) = 2 x 2 = 4 P(TAIL and HEAD or P(HEAD and TAIL) = = 2 st roll 2 nd roll 5 P( and ) = x = P( and ) = x 5 = 5 P( and ) = 5 x = P( and ) = 5 x 5 = 25 Use the tree diagram to answer: a. P( and ) = c. P( and ) or P( or ) = = 0 b. P( and ) = 25 d. P( and ) or P( and ) or P( and ) = = Page 5 of

6 . A bag contains 7 blue counters and red counters. A counter is taken out at random, the colour noted and put back into the bag. Another counter is then taken out and the colour noted. 9 a. 2 red counters are chosen 00 b. A blue and a red counter in any order are chosen Louise has a fruit juice and an apple almost every day. Complete the tree diagram: Juice juice Crisps crisps Crisps crisps 2. The probability that Peter eats breakfast is 0.4 a. What is the probability that he doesn t eat breakfast? 0. b. Draw a tree diagram and calculate: i. The probability that he eats breakfast 2 days in a row 0. ii. The probability that he eats breakfast at least once in two days 0.4 Challenge A bag contains 7 blue counters and red counters. A counter is taken out at random and not replaced. Another counter is then taken out and the colour noted. a. 2 red counters are chosen 90 b. A blue and a red counter in any order are chosen What is the probability that she not have juice or crisps? Page of