The cost of first-class postage in the United States increased approximately 5.4% in January of 2006 to 39 cents. What was the pre- January cost of the first-class stamp? Round your answer to the nearest penny.

A 5.4% increase means the new price is 105.4% of the old price. Divide $0.39 by 1.054 to find the pre-increase cost: $0.39 ÷ 1.054 ≈ $0.37. The pre-January cost was $0.37, choice D.

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