Find the area of the shaded portion if we know the outer circle has a diameter of 4 m and the inner circle has a diameter of 1.5 m.
6
9
O
12
15
12.6 m²
1.8 m²
18
43.2 m²
21
10.8 m?
Ma

The distribution of a sample of the outside diameters of pvc pipes approximates a symmetrical, bell-shaped distribution. the arithmetic mean is 14.0 inches, and the standard deviation is 0.1 inches. about 68% of the outside diameters lie between what two amounts?