Firms Y and Z both produce and sell small gasoline engines. The sales price is $200 per engine. Data for both firms at a sales volume of 50 units are as follows:

Firm Y Firm Z

Sales (50 units) $10,000 $10,000

Variable costs($50, $25) (2,500) (1,250 )

Total contribution margin $7,500 $8,750

Fixed costs (4,500) ( 5,750 )

Operating income (B) $3,000 $3,000

Required: From the existing level of sales, which firm's operating income (B) is more sensitive to changes in sales volume? Show calculations and round your answers to 2 decimal places.