At what time between 4 and 5 o’clock will the hands of a clock first be at right angles?
Correct answer A. 5 5/11 minutes past 4
Explanation
The first right angle needs 120 − 5.5M = 90, so M = 30/5.5 = 60/11 = 5 5/11. The time is 5 5/11 minutes past 4.
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