What is standard deviation of 200,220,240,230,280,320,250,270
just apply the formula. Here is a handy calculator to verify your work
>wink wink<
www.calculator.net/standard-deviation-calculator.html?numberinputs=200%2C220%2C240%2C230%2C280%2C320%2C250%2C270+&ctype=p&x=51&y=12