To solve this, we use the z-test.
z = (x – u) / σ
when x = 450
z = (450 – 550) / 100
z = -1
We use the standard distribution tables to find for P.
P = 0.1587
Since we are looking for values greater than x = 450, therefore:
1 – 0.1587 = 0.8413
This means that 84.13% have bladder volume larger than 450 mL.