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2.2.3 Central tendency, variation and standard deviation

Question 10

The number of faults found on each of 70 cars is summarised in the table below, where $a\,$ and $b\,$ are positive integers.

Number of faults	0	1	2	3	4
Frequency	12	$a$	20	$b$	6

The mean number of faults per car is exactly 2.

Show that $a + b = 32$ and $a + 3 b = 76$ .

[3]

Find the value of $a\,$ and the value of $b$ .

[2]

Write down the mode of the number of faults.

[1]

Markscheme

2.2.3 Central tendency, variation and standard deviation Questions

A Level
Maths
2.2.3 Central tendency, variation and standard deviation

39 exam-style questions on AQA A Level Maths 2.2.3 Central tendency, variation and standard deviation. Each one has a worked solution and a mark scheme showing where the marks go.

2.2.3 Central tendency, variation and standard deviation

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2.2.3 Central tendency, variation and standard deviation

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Question 10

The number of faults found on each of 70 cars is summarised in the table below, where $a\,$ and $b\,$ are positive integers.

Number of faults	0	1	2	3	4
Frequency	12	$a$	20	$b$	6

The mean number of faults per car is exactly 2.

Show that $a + b = 32$ and $a + 3 b = 76$ .

[3]

Find the value of $a\,$ and the value of $b$ .

[2]

Write down the mode of the number of faults.

[1]

Markscheme

2.2.3 Central tendency, variation and standard deviation Questions

A Level
Maths
2.2.3 Central tendency, variation and standard deviation

39 exam-style questions on AQA A Level Maths 2.2.3 Central tendency, variation and standard deviation. Each one has a worked solution and a mark scheme showing where the marks go.