As part of the work to perform a Monte Carlo simulation the following information about the unit variable operating costs that will be generated by a project is as follows:

Expected unit variable operating costs: $200

95% confidence interval forecast of unit variable operating costs: $170 to $230

If the above unit sales are distributed normally, compute the approximate standard deviation for unit variable operating costs.

Group of answer choices

$7.50

$30.00

$15.00

$60.00