Difficulty: Easy
Correct Answer: 4000
Explanation:
Introduction: Catching flies here scales with the number of spiders and with time, assuming a constant per-spider catch rate. We infer the rate from the base scenario and then scale to the larger numbers using direct proportionality (spiders × minutes × rate per spider-minute).
Given Data / Assumptions:
Concept / Approach: Let r be the number of flies caught by one spider per minute. Then total flies = spiders × minutes × r. Using the base case we find r, then apply it to the new case by multiplication without rounding since values are exact here.
Step-by-Step Solution:
Base: 10 = 10 * 10 * r → r = 10 / 100 = 0.1 flies per spider-minute New: Flies = 200 * 200 * 0.1 = 4000Verification / Alternative check: Proportion method: New/Base = (200/10) * (200/10) = 20 * 20 = 400. Then 10 * 400 = 4000, same result.
Why Other Options Are Wrong: 2000, 3000, 5000, 2500 are not consistent with the direct quadratic scaling in spiders and minutes based on the stated rate.
Common Pitfalls: Treating the relationship as linear in one factor only (either spiders or minutes). The catch count scales with both.
Final Answer: 4000
Discussion & Comments