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Probability of a single event Example A letter is selected at random from the word Mathematics. What is the probability that it is: a) a h b) a consonant c) a m?
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Example A bag contains 9 white balls, 8 green balls and 3 blue balls. One ball is selected at random. What is the probability that the ball is (a)white (b)green (c)red (d) not blue?
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Example A single card is drawn from a pack of 52 playing cards. Find the probability of the card being: (a)a Queen (b)a club (c)the Jack of hearts (d)an even number. (e)a picture card
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Example 26% of the population is overweight. What is the probability that a person selected at random is not overweight?
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Example Ten counters equal in size and shape are numbered 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 are placed in a bag. One counter is selected at random. What is the probability of selecting a counter which is (a) numbered 3 (b) a factor of 16 (c) greater than 7?
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Example The table below shows the distribution of the ages of people visiting a local dentist in the month of March. A person is selected at random to answer a survey. What is the probability that the person is aged between 15 and 30 years of age.
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Example The Bar chart below represents the favourite subjects of class 6B1. One student is selected at random. What is the probability that their favourite lesson is mathematics?
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Example A bag contains blue, red and green cards only. One card is taken at random from the bag. The table shows the probabilities of taking a blue card and a red card. ColourBlueRedGreen Probability0.30.5 (a) What is the probability of taking a yellow card from the bag? (b) What is the probability of taking a card that is not blue from the bag? (c) Complete the table to show the probability of taking a green card from the bag
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Example Emma has a box of counters. The counters are green, red or blue. She picks a counter at random. The table shows the probability that she picks a green counter and the probability that she picks a red counter. ColourProbability Green0.6 Red0.25 Blue (a) What is the probability that Emma picks a blue counter? (b) There are 10 red counters in the box. How many green counters are in the box?
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Relative Frequency Example A spinner with five edges numbered 1 to 5 is spun 20 times and the results are shown below. 1 4 3 3 4 5 1 2 1 3 4 5 1 3 4 2 2 1 5 4 Complete the table of relative frequencies below. Number on spinner 12345 Relative Frequency
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Example The Bumbleton and Stickton village football teams have played each other 50 times. Bumbleton have won 10 times, Stickton have won 35 times, and the teams have drawn 5 times. Estimate the probability that Stickton will win the next match
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Example Matthew decides to try to estimate the probability that toast lands butter-side-down when dropped. He drops a piece of buttered toast 50 times and observes that it lands butter-side-down 30 times. Estimate the probability that the toast lands butter-side-down.
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Example A drawing pin can land 'point up' or 'point down' when dropped. Jim drops a drawing pin 100 times and it lands "point up" 35 times. Estimate the probability of the drawing-pin landing "point up"
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Example A spinner has a red sector (R) and a yellow sector (Y). The arrow is spun 1000 times. The table shows the relative frequency of a red after different numbers of spins. a)How many times was a red obtained after 200 spins? b)Which relative frequency gives the best estimate of the probability of a red? Explain your answer.
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Example A dice is suspected of bias. Here are the results of 20 throws 3423156243 4311625653 (a) Use these results to calculate the relative frequency of each score Score123456 Relative frequency (b) Use the relative frequency to calculate how many times you would expect to score 3 in 60 throws of this dice. (c) Compare your answer to part (b) with the number of times you would expect to score 3 in 60 throws of a fair dice.
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