Cube root of a very small decimal: Find the cube root of 0.000027.

Difficulty: Easy

Correct Answer: .03

Explanation:


Introduction / Context:
We need the cube root of a small decimal. Recognize familiar cubes: 27 is 3^3, so 0.000027 relates directly to a scaled cube.


Given Data / Assumptions:

  • Number: 0.000027 = 27 / 10^6.
  • Use principal cube root (positive).

Concept / Approach:
For positive a, ∛(a/10^n) = ∛a / 10^(n/3) when n is a multiple of 3. Here n = 6 is divisible by 3, which makes evaluation straightforward.


Step-by-Step Solution:

0.000027 = 27 / 10^6.∛(27 / 10^6) = ∛27 / ∛(10^6) = 3 / 10^2 = 3/100 = 0.03.Therefore, cube root = 0.03.

Verification / Alternative check:
(0.03)^3 = 27 / 10^6 = 0.000027, confirming the result exactly.


Why Other Options Are Wrong:

  • .3^3 = 0.027, too large by a factor of 1000.
  • .003^3 = 2.7e-8, far too small.
  • “None of these” is not needed since .03 is present.

Common Pitfalls:
Mixing square-root logic with cube roots or miscounting decimal-place triplets for cube roots.


Final Answer:
.03

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