A cubical storage bin measures 2.5 m along every edge. What is its volume?

Class 8Cubes and Cube RootsCubes and Roots

Step-by-Step Solution

2. 5^{3} = 2.5 \times 2.5 \times 2.5 = 6.25 \times 2.5 = 15.625 m^{3}

. Stopping at

6.25 m^{3}

gives only the square, and

7.5 m^{3}

2.5 \times 3

. One decimal place cubed gives three decimal places, so 156.25 has the point in the wrong place.

Answer: B)

15.625 m^{3}

Both are repeated multiplication, but with key differences:

- A square is non-negative:

(- 5)^{2} = + 25

.
- A cube **keeps the sign**:

(- 5)^{3} = - 125

. (Three negatives stay odd → still negative.)
- Squares grow more slowly than cubes:

5^{2} = 25

5^{3} = 125. -

For square roots, only positive results (by convention). For cube roots, the sign matches the input: ∛

(- 27) = - 3

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