Answer:
19.92
Explanation:
To overfill 5% of the time ;
The Zscore (value) to the left of (1 - 0.05) = 0.95 is 1.645
Using this Zscore value with the Zscore formula :
Zscore = (x - μ) / σ
σ = 0.05 ; x = 20 ounce
Substituting into the Zscore formula :
1.645 = (20 - μ) / 0.05
1.645*0.05 = 20 - μ
0.08225 = 20 - μ
μ = 20 - 0.08225
μ = 19.91775
μ = 19.92