Answer: 204.76%
Step-by-step explanation:
In the earlier scenario, furniture maker manufactured 47 (42 non defective) pieces per 5 laborers working 8 hours day.
Thus, the productivity in terms of units per labor hour is as follows:

= 1.05
Similarly, after the process improvement, the productivity in units per labor hour would be:

= 3.2
Thus change in productivity would be calculated as:

= 2.047 × 100
= 204.76%
Thus, the productivity of non defective parts would increase by 204.76%.