Difficulty: Easy
Correct Answer: 0.4471
Explanation:
Introduction / Context:
We evaluate a common logarithm by breaking 2.8 into factors whose logs are known and using standard log identities.
Given Data / Assumptions:
Concept / Approach:
Write 2.8 = 28/10 = (4×7)/10, then apply log(A/B) = log A − log B and log(AB) = log A + log B.
Step-by-Step Solution:
Verification / Alternative check:
2.8 ≈ 10^0.4471 (since 10^0.4471 ≈ 2.8), confirming consistency with the computed value.
Why Other Options Are Wrong:
1.4471 is log 28; 2.4471 or 14.471 are orders of magnitude too large; 0.4471 is the only value matching log 2.8.
Common Pitfalls:
Forgetting to subtract 1 when converting from log 28 to log 2.8 (since 2.8 = 28/10) yields the common mistake 1.4471 instead of 0.4471.
Final Answer:
0.4471
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