2026 · Q79
N number of cubes each of side length equal to 10 cm are joined end to end in a row. If the total surface area of the resulting cuboid is 3800 cm², then what is the value of N?
Elementary MathematicsMensuration
- A8
- B9
- C10
- D12
Explanation
Joining N cubes of side 10 end to end gives a 10N × 10 × 10 cuboid. Its total surface area is 2(100N + 100N + 100) = 400N + 200. Setting 400N + 200 = 3800 gives 400N = 3600, so N = 9, option B.