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2.2.3 Central tendency, variation and standard deviation

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Question 5

Twenty values have mean 12, and for these values $∑x2=2960\sum x^2 = 2960$ .

One further value, $c$ , is added. The mean of the resulting 21 values is 12.5.

Find the value of $c$ .

[2]

Find the standard deviation of the 21 values.

[3]

The standard deviation of the original 20 values is 2. Explain why the standard deviation of the 21 values is larger.

[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

Question bank

2.2.3 Central tendency, variation and standard deviation

Easy Medium Hard

1 2 3 4 5 6 7 8 9 10 11

Question 5

Twenty values have mean 12, and for these values $∑x2=2960\sum x^2 = 2960$ .

One further value, $c$ , is added. The mean of the resulting 21 values is 12.5.

Find the value of $c$ .

[2]

Find the standard deviation of the 21 values.

[3]

The standard deviation of the original 20 values is 2. Explain why the standard deviation of the 21 values is larger.

[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.