what is difference between mean and ,stander deviation/mean

#2
regarding your first question: You will probably find a detailed answer in the introduction section of various statistic books or online contributions. Regarding the second question: I don't know what a "stranded deviation" is ;-) Jokes apart, do you really want to consider mean vs. (standard deviation)/mean or rather mean vs. mean/(standard deviation)?
 

Dragan

Super Moderator
#3
...what id difference between mean and stranded deviation/mean?
The standard deviation divided by the mean is referred to as the Coefficient of Variation. It's a relative measure of variability that does not depend on the units of measurement. And, it is typically expressed as a percentage.