Nested decimal radicals simplification: Evaluate √[(0.324 × 0.081 × 4.624) / (1.5625 × 0.0289 × 72.9 × 64)].
Aptitude
Square Root and Cube Root
Difficulty: Medium
Choose an option
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A24
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B2.40
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C0.024
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DNone of these
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E0.12
Answer
Correct Answer: 0.024
Explanation
Introduction / Context:This expression looks complicated but becomes simple when decimals are written as exact fractions and factors are canceled before taking the square root.
Given Data / Assumptions:
- Numerator: 0.324, 0.081, 4.624.
- Denominator: 1.5625, 0.0289, 72.9, 64.
- All are exact decimals (e.g., 1.5625 = 25/16; 0.0289 = 17^2/10^4).
Concept / Approach:Convert to prime-powered fractions, cancel common factors systematically, then take the square root at the end to avoid rounding.
Step-by-Step Solution:
0.324 = 81/250; 0.081 = 81/1000; 4.624 = 578/125 = 2 * 17^2 / 5^3.1.5625 = 25/16 = 5^2/2^4; 0.0289 = 17^2/10^4; 72.9 = 729/10 = 3^6/(2*5); 64 = 2^6.After cancellations, the inside reduces exactly to 9/15625.Therefore, the value is √(9/15625) = 3/125 = 0.024.Verification / Alternative check:Compute numerically with high precision: result ≈ 0.02400, confirming the exact fractional outcome.
Why Other Options Are Wrong:
- 24 and 2.40 are off by factors of 1000 and 100.
- “None of these” is unnecessary since 0.024 matches exactly.
- 0.12 is five times too large.
Common Pitfalls:Rounding mid-steps instead of canceling exactly; mixing percent and decimal interpretations.
Final Answer:0.024