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Probability. Probability objectives. Recap probability rules (5) Revise Probability scales (5) Calculate with probabilities (5). Starter. Place the following statements on this probability scale. a) You will meet the queen today b) It will rain today
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Probability objectives • Recap probability rules (5) • Revise Probability scales (5) • Calculate with probabilities (5)
Starter • Place the following statements on this probability scale. • a) You will meet the queen today • b) It will rain today • c) The next person to enter this room will be female • d) The sun will rise tomorrow
a b c d impossible Very unlikely Even chance Very likely Certain Starter • What could we replace the words with? • Percentages • Decimals • Fractions
1 3 2 4 5 6 4 3 Estimating probabilities • What are the chances of scoring a 4 on this spinner • Number of 4’s on the spinner 2 • Number of sections on the spinner 8 • P(4) = 2 = 1 8 4
1 3 2 4 5 6 4 3 Estimating probabilities • Write down the probabilities for the following.
1 3 2 4 5 6 4 3 Estimating probabilities • Probability of an event not occuring. • Probability of y not occurring P(y’) • Worked out as follows P(y’) = 1 - P(y) • P(2’) = 1 – P(2) • How many numbers are not 2 • How many sections are there
1 3 2 4 5 6 4 3 Estimating probabilities • Write down the probabilities not getting the following.
1 3 2 4 5 6 4 3 Estimating probabilities Extension • Therefore how would we work out the probability of getting a 1 and a 4? • Work out each probability then add them together Remembering that to add fractions the denominator must be the same.
1 3 2 4 5 6 4 3 Estimating probabilities • Write down the probabilities of getting both of the following values.
Assessment question • P(s) = P(w) = • P(b’) = P(even no.) = • P(w or 6) = P(3 or 5) = • P(s or even) = P(w or 5) = 1 3 5 6 2 7 8 4
Assessment • There are 52 cards in a normal pack of cards. There are four suits (hearts, spades diamonds and clubs) suits have numbered card 2- 10 then court cards jack, queen, king and an ace. What is the probability of taking: • The ace of spades • A king • A numbered card • A red card • A black 3
Assessment • So therefore how many cards are NOT • The ace of spades • A king A red card • A numbered card A black 3 • Probabilities must add up to 1 or 100% • Therefore 1 minus the probability of an event occurring equals the probability of the event not occurring P(A’) = 1 – P(A)
Plenary • Write down three points you have learnt about probability today.
Probability objectives • Recap probability rules (5) • Revise Probability scales (5) • Calculate with probabilities (5)