Multiple choice

A clock showing 8:20. After what time, the minute hand and hour hand will be making an angle of 90o? एक घड़ी में 8 बजकर 20 मिनट हुए है बतायें कि अब से किस समय बाद घंटे और मिनट की सुई के बीच समकोण बनेगा?

  1. 8: 30 10/11

  2. 8: 32 9/118

  3. 8: 27 3/11

  4. 8: 12 9/11
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

At 8:20, hour hand at 250° (8×30 + 20×0.5), minute hand at 120° (20×6). Angle = 250-120 = 130°. Minute hand gains 5.5° per minute on hour hand. To get to 90°, need to cover 40° at 5.5°/min: t = 40/5.5 = 7/11 minutes. Time = 8:20 + 7/11 min = 8:27 3/11.

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