2026 Aircraft Weight & Balance Complete Practice Test

CG is found by taking the weighted average of all weights along their lever arms. In practice, you sum the moments (weight times its arm) of every item, then divide by the total weight.

When you add ballast, you add both its weight and its moment. So the new CG equals (existing total moment + ballast weight times its arm) divided by (existing total weight + ballast weight). Here the ballast is 120 lb at 60 inches, contributing 120 × 60 = 7,200 in-lb of moment and increasing the total weight by 120 lb. The final CG is (existing moment + 7,200) divided by (existing weight + 120).

The option chosen reflects the result of that calculation with the problem’s other data. If you want to verify, use the formula L_final = (W0·L0 + 120·60) / (W0 + 120), where W0 and L0 are the original total weight and CG location from the rest of the problem.