Difficulty: Medium
Correct Answer: 800 km
Explanation:
Introduction / Context:Splitting a journey into equal halves by distance but different speeds requires summing the two leg times and equating to the given total time to solve for the half-distance.
Given Data / Assumptions:
Concept / Approach:Total time = x/60 + x/50. Solve for x, then total distance = 2x.
Step-by-Step Solution:
x/60 + x/50 = 14.666... hCommon denominator 300: (5x + 6x)/300 = 14.666... → 11x/300 = 44/3x = (44/3) * (300/11) = 400 kmTotal distance = 2x = 800 kmVerification / Alternative check:Time check: 400/60 = 6.666... h; 400/50 = 8 h; sum = 14.666... h as given.
Why Other Options Are Wrong:They result from arithmetic slips or misinterpreting “half the distance” vs. “half the time.”
Common Pitfalls:Confusing equal halves by distance with equal halves by time; forgetting to convert minutes to fractional hours.
Final Answer:800 km
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