As an investor, you want to determine if the ACME Corporation is managing its overhead costs and production costs well. Given the following situations, determine the change in operating income for each $($please show your work for credit$).$ For the following questions assume the company sells its products for $$4$ each. $1.$ Calculate the change in operating income if the contribution margin ratio is $35\%$ and there is a $10,000$ unit increase in sales. $2.$ Calculate the change in operating income if the unit contribution margin is $$2\mathrm{.}10$ and there is an increase of $$20,000$ in sales. $3.$ Calculate the change in operating income if the contribution margin ratio is $30\%$ and there is an increase in sales of $$30,000.4.$ Why do investors prefer that ACME has increasing operating income?