Difficulty: Medium
Correct Answer: 54 6/11 minutes past 4
Explanation:
Introduction / Context:
The original stem said “straight line,” but the options match known right-angle times. Applying the right-angle condition |30H − 5.5M| = 90 with H between 4 and 5 yields two solutions within the hour, one of which lies between 4:30 and 5:00.
Given Data / Assumptions (Recovery Applied):
Concept / Approach:
Solving yields M = 21 9/11 and M = 54 6/11. Only 54 6/11 is between 4:30 and 5:00.
Step-by-Step Solution:
Verification / Alternative check:
Substitute M = 54 6/11; angle equals 90° exactly.
Why Other Options Are Wrong:
50, 42, 46 minutes are not exact right-angle solutions from the formula.
Common Pitfalls:
Forgetting that the hour hand moves (0.5 deg per minute), hence 5.5M term.
Final Answer:
54 6/11 minutes past 4
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