Difficulty: Easy
Correct Answer: 25 days
Explanation:
Introduction / Context:This is a rates-combination problem using equivalent-team times. We find individual animal rates and sum them for the new team.
Given Data / Assumptions:
Concept / Approach:Compute per-day per-animal rates from the team times, add them, and invert to get time.
Step-by-Step Solution:
Rate(goat) = 1 / (4 * 50) = 1/200 per dayRate(sheep) = 1 / (6 * 50) = 1/300 per dayTeam rate = 2*(1/200) + 9*(1/300) = 1/100 + 3/100 = 1/25 per dayTime = 1 / (1/25) = 25 daysVerification / Alternative check:If they worked 25 days, they would do 25 * (1/25) = 1 job, confirming correctness.
Why Other Options Are Wrong:50, 75, 100 days correspond to incorrect combined rates.
Common Pitfalls:Failing to convert team times into per-animal rates before recombining.
Final Answer:25 days
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