If the mantissa of log10 3274 is 0.5150, find log10 32.74.
Aptitude
Logarithm
Difficulty: Easy
Choose an option
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A1.5150
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B2.5150
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C0.5150
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D1.5150
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ENone of these
Answer
Correct Answer: 1.5150
Explanation
Introduction / Context:In common logarithms, log10 N = characteristic + mantissa, where the mantissa depends only on the significant digits (order-of-magnitude independent). Moving the decimal point changes the characteristic but preserves the mantissa.
Given Data / Assumptions:
- log10 3274 has mantissa 0.5150 ⇒ log10 3274 = 3.5150.
- We need log10 32.74 (same significant digits, decimal shifted left two places).
Concept / Approach:
- Shifting decimal left by k reduces the characteristic by k.
- Mantissa remains 0.5150 (same significand 3.274 × 10^1 vs 3.274 × 10^3).
Step-by-Step Solution:
log10 3274 = 3.515032.74 = 3274 × 10^(−2) ⇒ log10 32.74 = 3.5150 − 2 = 1.5150Verification / Alternative check:Direct estimation: 32.74 lies between 10 and 100, so characteristic must be 1; mantissa stays 0.5150 ⇒ 1.5150.
Why Other Options Are Wrong:
- 2.5150 would correspond to 327.4; 0.5150 would correspond to 3.274.
Common Pitfalls:
- Changing mantissa when only the decimal position changes.
Final Answer:1.5150