Question

Question 1 Find the mean and variance for the data 6, 7, 10, 12, 13, 4, 8, 12

Class X1 - Maths -Statistics Page 371

Answer 1

For finding mean use the formula,
$mean (\overline{x})=\frac{\sum{x_i}}{n}$
and for finding variance use the formula,
$variance=\frac{\sum{x_i^2}}{n}-(\frac{\sum{x_i}}{n})^2$
see attachment ,here,
$\sum{x_i}=72,n=8\\\\\therefore\overline{x}=\frac{\sum{x_i}}{n}\\\\=\frac{72}{8}=9\\\\\\and\: variance=\frac{\sum{x_i^2}}{n}-(\frac{\sum{x_i}}{n})^2\\\\=\frac{722}{8}-(\frac{722}{8})^2\\\\=90.25-81=9.25$

hence, answer is 9.25