(a) Cost of money rate is either—

(1) The interest rate determined by the Secretary of the Treasury under Public Law 92-41 (85 Stat. 97); or

(2) The time-weighted average of such rates for each cost accounting period during which the capital asset is being constructed, fabricated, or developed.

(b) Representative investment is the calculated amount considered invested by the contractor during the cost accounting period to construct, fabricate, or develop the capital asset.