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2.2.3 Central tendency, variation and standard deviation

Question 12

The number of faults found on each car in a batch is summarised in the table below, where $a\,$ is a positive integer.

Number of faults	0	1	2	3	4
Frequency	10	$a$	18	9	3

The mean number of faults per car is exactly 1.5.

Find the value of $a$ .

[3]

Find the standard deviation of the number of faults.

[2]

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 12

The number of faults found on each car in a batch is summarised in the table below, where $a\,$ is a positive integer.

Number of faults	0	1	2	3	4
Frequency	10	$a$	18	9	3

The mean number of faults per car is exactly 1.5.

Find the value of $a$ .

[3]

Find the standard deviation of the number of faults.

[2]

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.