The diameter of circles (in mm) drawn in a design are given below:

Calculate the standard deviation and mean diameter of the circles.

Explanation

Let assumed mean `A=42.5` and `h=4`
Mean `=A+h . (sumf_(i)d_(i))/(sumf_(i))`
`=42.5+(4xx25)/100=43.5mm`
Standard deviation
`=hsqrt((sumf_(i)d_(i)^(2))/N-((sumf_(i)d_(i))/N)^(2))`
`=4sqrt(199/100-(25/100)^(2))=4sqrt(1.99-0.0625)`
`=4xxsqrt(1.9275)=4xx1.3883)`
`=5.5532mm~~5.55mm`