An airplane has tare weight 1,200 lb at CG 24 inches. If you add a 300 lb payload at 60 inches, what is the new CG in inches?

• A. 32.0 inches
• B. 31.2 inches
• C. 29.5 inches
• D. 28.0 inches

Answer: (B)

Center of gravity is where the overall weight would balance, found by the weighted average of the positions (moments) of all weights. Add up each weight times its distance (arm) from a reference, then divide by the total weight.

Tare weight contributes a moment of 1200 lb × 24 in = 28,800 lb-in.

Payload contributes a moment of 300 lb × 60 in = 18,000 lb-in.

Total weight becomes 1200 + 300 = 1,500 lb, and total moment becomes 28,800 + 18,000 = 46,800 lb-in.

New CG = total moment / total weight = 46,800 / 1,500 = 31.2 inches.

So the new CG is 31.2 inches. The result makes sense because adding weight farther aft or forward shifts the CG toward that location; here the payload at 60 inches pulls the CG forward from the original 24 inches to 31.2 inches.