Diana Company, a sole proprietorship, sells only one product. The regular price is $160. Variable costs are 55% of this selling price, and fixed costs are $8,400 a month. Management decides to decrease the selling price from $160 to $145 per unit. Assume that the cost of the product and the fixed operating expenses are not changed by this pricing decision. (a) At the original selling price of $160 a unit, what is the contribution margin ratio? (b) At the original selling price of $160 a unit, what dollar volume of sales per month is required for Diana Company to break-even? (c) At the original selling price of $160 a unit, what dollar volume of sales per month is required for Diana Company to earn a monthly operating income of $6,500? (d) At the reduced selling price of $145 a unit, what is the contribution margin ratio? (e) At the reduced selling price of $145 a unit, what dollar volume of sales per month is required to break-even