Evaluate [(0.96)<sup>3</sup> − (0.1)<sup>3</sup>] ÷ [(0.96)<sup>2</sup> + 0.096 + (0.1)<sup>2</sup>].
Aptitude
Decimal Fraction
Difficulty: Easy
Choose an option
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A0.85
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B0.86
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C0.89
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D0.96
Answer
Correct Answer: 0.86
Explanation
Problem restatementCompute the value of the fraction where the numerator is a3 − b3 with a = 0.96, b = 0.10, and the denominator is a2 + ab + b2.
Given data
- a = 0.96
- b = 0.10
- ab = 0.096
Concept/ApproachUse the identity a3 − b3 = (a − b)(a2 + ab + b2). Dividing (a3 − b3) by (a2 + ab + b2) simplifies to a − b.
Step-by-Step calculation[(0.96)3 − (0.10)3] ÷ [(0.96)2 + (0.96)(0.10) + (0.10)2] = 0.96 − 0.10= 0.86
Verification/AlternativeDirect substitution into the identity confirms immediate cancellation of the common factor.
Common pitfallsComputing all powers numerically instead of recognizing the factorization shortcut.
Final Answer0.86