Grawburg Incorporated maintains a call center to take orders, answer questions, and handle complaints. The costs of the call center for a number of recent months are listed below: April May June July August September October November Calls Taken 7,340 7,309 7,350 7,347 7,316 7,329 7,370 7,355 Call Center Cost $ 79,575 $ 79,384 $ 79,641 $ 79,603 $ 79,438 $ 79,509 $ 79,754 $ 79,666 Management believes that the cost of the call center is a mixed cost that depends on the number of calls taken. Required: Estimate the variable cost per call and fixed cost per month using the least-squares regression method. (Round the "Variable cost" to 2 decimal places and the "Fixed cost" to the nearest dollar amount.) per call Variable cost Fixed cost per month A company sold a total of 1,000 units for total sales revenue of $100,000. The company incurred total variable expenses of $65,000 and total fixed expenses of $ 30,100. Based on this, the company reported a total contribution margin of $35,000 and net operating income of $ 4,900. Use this information to answer the following questions. Assume that all units are within the relevant range. Calculate the estimated percent increase in net operating income for a 5% increase in sales. (Hint: Use the degree of operating leverage you already computed.) (Round your intermediate calculations and final answer to 2 decimal places.) % Increase in net operating income Calculate the degree of operating leverage. (Round your answer to 2 decimal places.) Degree of operating leverage Calculate the margin of safety in dollars and the margin of safety percentage. Margin of safety in dollars Margin of safety percentage %