Difficulty: Easy
Correct Answer: 8
Explanation:
Introduction / Context:
This is a direct percent-back calculation: if some percentage of a quantity is known, recover the rate. Such problems are common in discounts, interest, and concentration questions.
Given Data / Assumptions:
Let p be the percentage value (not decimal). Then p% of 130 equals 10.4.
Concept / Approach:
Translate to equation: (p/100) * 130 = 10.4. Solve for p by isolating it: p = 10.4 * 100 / 130. Simplify the fraction carefully to avoid arithmetic errors.
Step-by-Step Solution:
Verification / Alternative check:
8% of 130 = 0.08 * 130 = 10.4. This confirms correctness.
Why Other Options Are Wrong:
0.8 and 0.08 confuse percent with decimal fraction; 80 is ten times larger than required; 0.8% would yield only 1.04.
Common Pitfalls:
Forgetting to multiply by 100 when converting from decimal proportion to percent, or misplacing the decimal during division.
Final Answer:
8
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