Design of Experiment:

The two possible design variables:
1. Air Exhaust Area (x1) :30 mm2 (low) 40 mm2 (high)
2. N95 Mask Layers (x2) : 1 layer (low) 4 layers (high)

The filtration efficiency after 7 hours of continuous use will be the performance variable.

Data Analysis:

It should be evident that by having a low x2 value, we can minimize variation. Therefore there should only be one layer of N95 masks.

It should be evident that by having a low x1 value, we can minimize Ŷ. Therefore the area should be 30 mm2.