What is the total surface area of a cuboid whose dimensions are 12cm × 8cm × 3cm?

Analyze the question: We need the total surface area of a cuboid with length 12 cm, width 8 cm and height 3 cm.

Concept: A cuboid has 6 rectangular faces, in 3 pairs of equal faces. The formula is:

Total Surface Area = 2(lw + lh + wh)

Solution:

• lw = 12 × 8 = 96
• lh = 12 × 3 = 36
• wh = 8 × 3 = 24

Sum = 96 + 36 + 24 = 156

Total Surface Area = 2 × 156 = 312 cm²

Check against the options: Option B (96), C (36) and D (24) are the areas of single faces, which is a common trap. Only A matches the full total.

Answer: A. 312 cm²

Tip: Do not stop at the sum of three faces. Always multiply by 2, since each face has an opposite partner. If an option equals just one face area (like 96, 36 or 24), it is a distractor.