please answer all 4 multiple choice questions

A responsibility center in which a manager is responsible for revenues, cost, and investment is an) cost center. revenue center profit center. investment center None of these. If the accounts receivable turnover is 42 days, what is the account receivable turnover ratio (assuming a 365 day year)? 7.14 times 8.69 times 4.52 times None of these When 10,000 units are produced, variable costs are $6 per unit. Therefore, when 20,000 units are produced: Variable costs will total $120,000. Variable costs will total $60,000. Variable unit costs will increase to $12 per unit. Variable unit costs will decrease to $3 per unit. The margin of safety is equal to: Sales - Net operating income. Sales - (Variable expenses/Contribution margin). Sales - (Fixed expenses/Contribution margin ratio). Sales - (Variable expenses + Fixed expenses)