Activity- statistics problems

=Problem 1= If n =10, = 12 and $$\sum{x^2}= 1530 $$

=INTERPRETATION OF PROBLEM=

=Previous knowledge=

=Solution=

$$\frac{\sum x}{n}=\bar x $$

$$\sum {x} ={\bar x \times {n}} $$

$$\sum {x} ={12 \times {10}} $$

$$\sum {x} =120 $$ σ=$$\sqrt{\frac {\sum {x^2}}{n}-({\frac{\sum x}{n})^2}}$$ σ=$$\sqrt{\frac{1530}{10}-{144}}$$ σ=$$\sqrt{153-144}$$ σ=$$\sqrt{9}$$ σ=3