Each Day a Firm Produces 50 Products Worth $40 Each

Each day a firm produces 50 products worth $40 each. Raw materials cost per unit are $12. The firm uses 4 workers on an eight-hour shift earning $10 per hour each. What is the multifactor productivity ratio?

A) 1.82
B) 0.77
C) 3.16
D) 0.12
E) 2.17