Approximation with percentages: What approximate value should replace the question mark (?) so that ?% of 218 ≈ (3 1/3) × 3.312 ?
Correct Answer: 5
Introduction / Context:This approximation problem combines a percentage of a number with a mixed-number multiplication. We first estimate the right-hand side value, then convert it into a percentage of 218 to identify the closest option.Given Data / Assumptions:
- Target: ?% of 218 ≈ (3 1/3) × 3.312.
- 3 1/3 = 10/3 ≈ 3.333…
- All computations are to be treated by sensible rounding.
Concept / Approach:Compute the right side: (10/3) * 3.312 ≈ 11.04. Then solve (?/100) * 218 ≈ 11.04, so ? ≈ (11.04 / 218) * 100. Match the nearest option.Step-by-Step Solution:
Compute RHS: (10/3) * 3.312 ≈ 11.04.Set (?/100) * 218 ≈ 11.04.? ≈ (11.04 / 218) * 100 ≈ 5.06%.Nearest listed percentage: 5%.Verification / Alternative check:Check 5% of 218 = 0.05 * 218 = 10.9, which is very close to 11.04; the slight difference is acceptable for an approximation question.Why Other Options Are Wrong:
- 2.5: Yields roughly 5.45, far below ~11.04.
- 10: Gives 21.8, almost double the target.
- 15: Gives 32.7, much too large.
Common Pitfalls:Misreading 3 1/3 or converting it inaccurately, or forgetting to turn the computed decimal back into a percentage of 218. Always compare your estimate with the multiple-choice grid to select the closest feasible option.Final Answer:
5