We have containers that should be filled with 0.55L each, the standard deviation from the machine error in filling is 0.07L. A box of these containers contain 12 of them, what is the standard deviation in volume of the entire box?

What i'm thinking here is that the variance is simply 0.07^2, and that the variance of a constant times a stochastic variable is the variance of the variable multiplied with the square of said constant. Which would mean that the standard deviation for the entire box should be sqrt(12^2 * 0.07^2). That answer is 0.84 but Maple TA (our electronic exercise system) doesn't accept the answer. I've just started statistics so i might be all wrong, anyone have some insight?

In advance, thanks