UPSC Prelims 2024·CSAT·Quantitative Aptitude·Geometry and Mensuration

125 identical cubes are arranged in the form of cubical block. How many cubes are surrounded by other cubes from each side?

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Last updated 23 May 2026, 3:31 pm IST
  1. A27Correct
  2. B25
  3. C21
  4. D18

Explanation

The large cubical block is formed by 125 identical cubes. Since 5 x 5 x 5 = 125, the large block has dimensions of 5 cubes by 5 cubes by 5 cubes. A cube is "surrounded by other cubes from each side" if it is not on the outer surface of the larger block. This means we need to find the number of cubes in the inner core of the 5x5x5 block. To find the dimensions of this inner core, we subtract 2 from each dimension of the outer block (1 for the layer removed from one side and 1 for the layer removed from the opposite side). New length = 5 - 2 = 3 New width = 5 - 2 = 3 New height = 5 - 2 = 3 So, the inner core of cubes that are completely surrounded forms a 3x3x3 cube. The number of cubes in this inner core is 3 x 3 x 3 = 27. Therefore, 27 cubes are surrounded by other cubes from each side. Analyzing the options: A) 27: This matches our calculation for the inner core of cubes. B) 25: Incorrect. C) 21: Incorrect. D) 18: Incorrect. The final answer is A.
Quantitative Aptitude: 125 identical cubes are arranged in the form of cubical block. How many cubes are surrounded by other cubes from each si

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