#### Answer

Plant B

#### Work Step by Step

Plant A:
μ: 0.2 σ:0.02
$P(.18\leq x \leq .22 )$ = $P(\frac{.18-.20}{0.02} \leq z \leq \frac{0.22-0.2}{0.02})$ =$P(-1 \leq z \leq 1 )$ =0.8413-.1587= 0.6826
Plant B:
μ: 0.19 σ:0.01
$P(0.18\leq x \leq 0.22 )$ = $P(\frac{0.18-0.19}{0.01} \leq z \leq \frac{0.22-0.01}{0.01})$ =$P(-1 \leq z \leq 3 )$ =0.9987-0.1587 = 0.84
Plant B is producing the greater proportion of pints that contain between 18% and 22% air, because the probability is higher.