Question

The following information is related to the sample of the size of  \(60, \sum x^2=18000, \ \sum x=960\), So variance is

A. 55

B. 44

C. 22

D. 16

1. D
2. B
3. A
4. C

Answer 1

Correct Answer - Option 2 : B

Given:

Sample size = 60

\(\sum x^2=18000, \ \sum x=960\)

Formula used:

\({\rm{Variance\;}} = {\rm{\;}}\frac{1}{{\rm{n}}}\sum {{\rm{x}}^2}\; - \;{\left( {\frac{{\sum {\rm{x}}}}{{\rm{n}}}} \right)^2}\)

Where, 

n = sample rate

Calculation:

Variance

⇒ (1/60) × 18000 - (960/60)²

⇒ 300 - (16)²

⇒ 300 - 256

⇒ 44

∴ The variance is 44.