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Either paper 3 marks
Ben spins a fair spinner with 8 equal sections numbered 1 to 8, and flips a fair coin.
(a)State the number of possible outcomes.
(b)Calculate the probability that he gets a head and a number greater than \(1\).
Show answer
(a) \(16\)
(b) \(\frac{7}{16}\)Each of the 8 numbers on the spinner can come up with a head or with a tail. Listing them systematically gives H1, H2, ... up to H8, and then T1, T2, ... up to T8.
\(2 \times 8 = 16\) outcomes.
The numbers greater than 1 are 2 up to 8, which is 7 numbers.
Each one gives one outcome with a head, so 7 of the 16 outcomes win.
\(P = \frac{ 7 }{ 16 }\)
As a fraction in its simplest form this is \(\frac{7}{16}\).
- (b) M17 winning outcomes out of 16
- (b) A1probability \(\frac{7}{16}\)
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Either paper 4 marks
A fair spinner has five sections, labelled A to E. The spinner is spun once.
(a)Complete these statements.
The spinner is most likely to land on section ________
The spinner is equally likely to land on sections ________ and ________
(b)Two different spinners are spun. One spinner has sections labelled with letters. The other spinner has sections labelled with numbers.
Here is a list of all the possible outcomes.
S 1, U 1, P 1, R 1, S 2, U 2, P 2, R 2, S 3, U 3, P 3, R 3
Show the possible sections on the two spinners.
Letter spinner: ________
Number spinner: ________
Show answer
(a) Most likely: section E. Equally likely: sections A and D.
(b) Letter spinner: S, U, P, R. Number spinner: 1, 2, 3.The more of the spinner a section takes up, the more likely the spinner is to land on it.
Section E is the largest, so the spinner is most likely to land on section E.
Sections A and D are the same size and no other two sections match, so the spinner is equally likely to land on sections A and D.
Each outcome is one section from each spinner, so a section appears many times in the list. Write each different one once.
The letters that appear are S, U, P, R, which makes 4 sections.
The numbers that appear are 1, 2, 3, which makes 3 sections.
Check: \(4 \times 3 = 12\), the number of outcomes in the list.
- (a) B1section E, the largest section
- (a) B1sections A and D, the only two sections the same size
- (b) B1letter spinner sections S, U, P, R, each used once
- (b) B1number spinner sections 1, 2, 3, each used once
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Either paper 4 marks
Two fair six-sided dice are rolled and the two scores are added together.
The sample space diagram shows every possible total. The score on the first die is down the side and the score on the second die is along the top.
+ 1 2 3 4 5 6 1 2 3 4 5 6 7 2 3 4 5 6 7 8 3 4 5 6 7 8 9 4 5 6 7 8 9 10 5 6 7 8 9 10 11 6 7 8 9 10 11 12 (a)Find the probability that the total is \(4\).
(b)Find the probability that the total is greater than \(9\).
Show answer
(a) \(\frac{1}{12}\)
(b) \(\frac{1}{6}\)The grid has \(6 \times 6 = 36\) cells and each one is equally likely.
Counting the cells that show 4 gives 3 of them.
\(P(\text{total} = 4) = \frac{ 3 }{36}\)
As a fraction in its simplest form this is \(\frac{1}{12}\).
The totals greater than 9 are the ones in the bottom right corner of the grid. Counting them gives 6 cells out of 36.
\(P(\text{total} > 9) = \frac{ 6 }{36}\)
As a fraction in its simplest form this is \(\frac{1}{6}\).
- (a) M1counting the cells showing 4: 3 out of 36
- (a) A1probability \(\frac{1}{12}\)
- (b) M1counting the totals greater than 9: 6 out of 36
- (b) A1probability \(\frac{1}{6}\)
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Either paper 4 marks
Spinner A has four equal sections numbered \(5\), \(6\), \(7\) and \(8\).
Spinner B has four equal sections numbered \(6\), \(7\), \(8\) and \(9\).
Both spinners are spun once and the two numbers are added together. Part of the sample space diagram has been filled in.
+ 6 7 8 9 5 11 12 13 14 6 12 13 14 15 7 13 14 15 16 8 (a)Complete the sample space diagram.
(b)Find the probability that the total is \(16\).
Show answer
(a) The bottom row reads 14, 15, 16, 17
(b) \(\frac{1}{8}\)The bottom row is for a score of 8 on spinner A, so add 8 to each of the spinner B numbers in turn:
\(8 + 6 = 14\), \(8 + 7 = 15\), \(8 + 8 = 16\), \(8 + 9 = 17\)
The completed grid has \(4 \times 4 = 16\) equally likely cells.
2 of them show a total of 16.
\(P(\text{total} = 16) = \frac{ 2 }{16}\)
As a fraction in its simplest form this is \(\frac{1}{8}\).
- (a) M1adding 8 to each of the spinner B numbers
- (a) A1bottom row 14, 15, 16, 17
- (b) M12 cells showing 16 out of 16
- (b) A1probability \(\frac{1}{8}\)
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Either paper 4 marks
Two fair six-sided dice are rolled. The smaller score is subtracted from the larger one, so the difference is never negative.
The sample space diagram shows every possible difference. The score on the first die is down the side and the score on the second die is along the top.
Difference 1 2 3 4 5 6 1 0 1 2 3 4 5 2 1 0 1 2 3 4 3 2 1 0 1 2 3 4 3 2 1 0 1 2 5 4 3 2 1 0 1 6 5 4 3 2 1 0 (a)Calculate the probability that the difference is \(2\).
(b)Calculate the probability that the difference is greater than \(2\).
Show answer
(a) \(\frac{2}{9}\)
(b) \(\frac{1}{3}\)There are 36 equally likely cells in the grid.
A difference of 2 appears 8 times, half of them above the diagonal of zeros and half below it.
\(P(\text{difference} = 2) = \frac{ 8 }{36}\)
As a fraction in its simplest form this is \(\frac{2}{9}\).
Count the cells showing a difference bigger than 2. They sit in the two corners furthest from the diagonal, and there are 12 of them.
\(P(\text{difference} > 2) = \frac{ 12 }{36}\)
As a fraction in its simplest form this is \(\frac{1}{3}\).
- (a) M18 cells showing a difference of 2 out of 36
- (a) A1probability \(\frac{2}{9}\)
- (b) M112 cells showing a difference greater than 2 out of 36
- (b) A1probability \(\frac{1}{3}\)
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Either paper 5 marks
Omar spins two spinners and multiplies the two numbers together.
The first spinner has the numbers \(1\), \(2\), \(3\) and \(4\) on it. The second spinner has the numbers \(1\), \(5\) and \(9\) on it.
The table shows every possible product.
1 5 9 1 1 5 9 2 2 10 18 3 3 15 27 4 4 20 36 Both spinners are fair.
(a)State the number of possible outcomes.
(b)Work out the probability that the product is an even number.
(c)Work out the probability that the product is greater than \(5\).
Show answer
(a) \(12\)
(b) \(\frac{1}{2}\)
(c) \(\frac{7}{12}\)The table has \(4\) rows and \(3\) columns, and every cell is one outcome.
\(4 \times 3 = 12\)
Count the even numbers in the table. There are \(6\) of them, out of \(12\) cells altogether.
\(P = \frac{ 6 }{12} = \frac{1}{2}\)
Go through the table and count the cells holding a number bigger than \(5\). There are \(7\) of them.
\(P = \frac{ 7 }{12} = \frac{7}{12}\)
- (b) M1counting the even products: 6 out of 12
- (b) A1probability \(\frac{1}{2}\)
- (c) M1counting the products greater than 5: 7 out of 12
- (c) A1probability \(\frac{7}{12}\)
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Either paper 5 marks
In a game, two fair spinners are spun.
Spinner A
Spinner B
If the numbers the arrows land on are different, the score is the lower number.
If the numbers the arrows land on are the same, the score is 0.
Part of the table of possible scores is shown.
Spinner B Spinner A 1 4 1 5 5 4 1 0 4 6 1 1 5 (a)Complete the table to show the possible scores.
(b)Write down the probability that the score is an odd number.
(c) The same game is played using spinners C and D. The numbers on spinner C are shown. Spinner D has two sections labelled p and q. All the numbers on spinner D are greater than 0. Spinner C Spinner D The table shows some of the possible scores.
Write the missing numbers p and q on spinner D.Spinner D Spinner C 9 1 q p 4 4 1 10 9 1 8 8 8 1 7 Show answer
(a) Row 5: 1, 4, 1, 0. Row 4: 1, 0, 1, 4. Row 6: 1, 4, 1, 5.
(b) \(\frac{7}{12}\)
(c) \(p = 8\) and \(q = 7\)For each cell compare the number on spinner A with the number on spinner B. If they are the same the score is 0, otherwise the score is the lower of the two numbers.
Row 5: 5 and 1 are different, so take the lower, score 1. 5 and 4 are different, so take the lower, score 4. 5 and 1 are different, so take the lower, score 1. 5 and 5 are the same, score 0.
Row 4: 4 and 1 are different, so take the lower, score 1. 4 and 4 are the same, score 0. 4 and 1 are different, so take the lower, score 1. 4 and 5 are different, so take the lower, score 4.
Row 6: 6 and 1 are different, so take the lower, score 1. 6 and 4 are different, so take the lower, score 4. 6 and 1 are different, so take the lower, score 1. 6 and 5 are different, so take the lower, score 5.
The completed table has \(3 \times 4 = 12\) equally likely cells, and a number on two sections of spinner B fills two columns.
The score 0 is even, so it is not counted as odd. There are \(7\) odd scores in the table.
\(P = \frac{ 7 }{12} = \frac{7}{12}\)
Use the one score shown in each of the columns p and q, with the number on spinner C for its row.
Column p, row 10: the score is 8. The score is not 0, so the numbers are different and the score is the lower one. It is below the number on C, so it is the number on D.
\(p = 8\)
Column q, row 8: the score is 7. The score is not 0, so the numbers are different and the score is the lower one. It is below the number on C, so it is the number on D.
\(q = 7\)
- (a) M1same numbers score 0, otherwise the lower number
- (a) A1all twelve scores correct
- (c) B1p = 8
- (c) B1q = 7
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Either paper 6 marks
A number is picked at random from the first three positive odd numbers.
A number is picked at random from the first four positive odd numbers.
The two numbers are multiplied to get a score.
Here is part of the table of possible scores.
× 3 5 7 1 1 3 5 7 9 15 21 5 5 25 (a)Complete the table.
(b)What is the probability that the score is a square number? Give your answer as a fraction in its simplest form.
Show answer
(a) Missing number at the top: 1. Missing number at the side: 3. Missing scores, reading along the rows from the top: 3, 15, 35
(b) \(\frac{1}{4}\)The top of the table is the first four positive odd numbers, so the missing number there is \(1\).
The side of the table is the first three positive odd numbers, so the missing number there is \(3\).
Each score is the number at the side multiplied by the number at the top. Multiplying each matching pair gives the three missing scores, in the order they are read along the rows: \(3 \times 1 = 3\), \(5 \times 3 = 15\) and \(5 \times 7 = 35\).
This is the completed table. Each score that is a square number is in bold.
The number of scores in bold is \(3\). The table has \(3 \times 4 = 12\) equally likely outcomes, so \(P = \frac{ 3 }{12}\) The highest common factor of \(3\) and \(12\) is \(3\). Dividing the top and the bottom by it gives the simplest form. \(P = \frac{1}{4}\)× 1 3 5 7 1 1 3 5 7 3 3 9 15 21 5 5 15 25 35 - (a) B1missing number at the top \(1\)
- (a) B1missing number at the side \(3\)
- (a) B1missing scores \(3\), \(15\), \(35\)
- (b) M1counts each score that is a square number in the completed table, \(3\) in total
- (b) A1\(\frac{ 3 }{12}\), as there are \(12\) outcomes
- (b) A1in simplest form, \(\frac{1}{4}\)
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Either paper 3 marks
Grace spins a fair spinner with 8 equal sections numbered 1 to 8, and flips a fair coin.
(a)Write down the number of possible outcomes.
(b)Work out the probability that she gets a head and a number greater than \(5\).
Show answer
(a) \(16\)
(b) \(\frac{3}{16}\)Each of the 8 numbers on the spinner can come up with a head or with a tail. Listing them systematically gives H1, H2, ... up to H8, and then T1, T2, ... up to T8.
\(2 \times 8 = 16\) outcomes.
The numbers greater than 5 are 6 up to 8, which is 3 numbers.
Each one gives one outcome with a head, so 3 of the 16 outcomes win.
\(P = \frac{ 3 }{ 16 }\)
As a fraction in its simplest form this is \(\frac{3}{16}\).
- (b) M13 winning outcomes out of 16
- (b) A1probability \(\frac{3}{16}\)
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Either paper 4 marks
A fair spinner has five sections, labelled A to E. The spinner is spun once.
(a)Complete these statements.
The spinner is most likely to land on section ________
The spinner is equally likely to land on sections ________ and ________
(b)Two different spinners are spun. One spinner has sections labelled with letters. The other spinner has sections labelled with numbers.
Here is a list of all the possible outcomes.
V 1, Q 1, S 1, U 1, V 2, Q 2, S 2, U 2, V 3, Q 3, S 3, U 3
Show the possible sections on the two spinners.
Letter spinner: ________
Number spinner: ________
Show answer
(a) Most likely: section B. Equally likely: sections A and E.
(b) Letter spinner: V, Q, S, U. Number spinner: 1, 2, 3.The more of the spinner a section takes up, the more likely the spinner is to land on it.
Section B is the largest, so the spinner is most likely to land on section B.
Sections A and E are the same size and no other two sections match, so the spinner is equally likely to land on sections A and E.
Each outcome is one section from each spinner, so a section appears many times in the list. Write each different one once.
The letters that appear are V, Q, S, U, which makes 4 sections.
The numbers that appear are 1, 2, 3, which makes 3 sections.
Check: \(4 \times 3 = 12\), the number of outcomes in the list.
- (a) B1section B, the largest section
- (a) B1sections A and E, the only two sections the same size
- (b) B1letter spinner sections V, Q, S, U, each used once
- (b) B1number spinner sections 1, 2, 3, each used once