What is the weight of pressure treated lumber?

Approximately 0.024 lbs per cubic inch. A common pressure-treated 2x6 that is 12 feet long (2x6x144 inches) will weigh 38 to 40 pounds.

Example: a 4" x 12" x 10' pressure treated beam
(note that 10' = 120 inches)

4 x 12 x 120 = 5760 * 0.024 = approx 138 lbs for the beam

Per cent moisture content has a dramatic impact on wood weight and especially so in the case of PT lumber, which is artificially infused with water during manufacturing and typically takes some weeks and months to dry to equilibrium. I came across the above in trying to research how much moisture my current PT decking has, and the above formula gives 10.0 lbs for the 1" x 5.5" x 76" boards I have (I've got about a dozen). However, their actual weights (measured just this morning) vary between 8.6 lbs and 13.2 lbs (i.e. an 86% to 132% variation from the above formula). Is it even possible (reasonable?) to specify weight for PT lumber without also identifying its per cent moisture content?
So the above would be an average weight.