Question

If for a sample of size 60, we have the following information \[\sum_{} x_i^2 = 18000\] and \[ \sum_{} x_i = 960 \] , then the variance is

 

Options

• 6.63   

•  16  

• 22    

• 44 

Answer 1

Given:

\[\sum_{} x_i^2 = 18000\] ,  \[ \sum_{} x_i = 960 \]   and n = 60 

∴ Variance

\[= \frac{\sum_{} x_i^2}{n} - \left( \frac{\sum_{} x_i}{n} \right)^2 \]

\[ = \frac{18000}{60} - \left( \frac{960}{60} \right)^2 \]

\[ = 300 - 256\]

\[ = 44\]