how to obtain mean, standard deviation from data if it is given arranged in classes?

n=no. of readings

RDG=individual readings

AVG= mean or average readings

STD=standard deviation

(STD)^2=sume of [(RDG-AVG)^2]/n

AVG=sum of individual readings divided by no. of readings

probability 99.73% RDG falls within AVG +/- 3*(STD)

Alternative=you can use statistic calculator or computer with software Lotus123 using @ funnction such as @AVG & @STD

by tony q

Mean, just add all x (data points) and divide by n (number of sample). The standard deviation is a little more complicated with it's formula but all it means is how far any one point is away from the mean. So if the mean is for example, 12 and one of your points is 10 then the standard deviation of that point is -2. I don't quite understand what you mean by arranged in classes? Hope this helps a little. good luck!

Try 8 (repeated 15 times) and 12 repeated 15 times n= 30, mean 10, sd 2