Multiple choice

A clock showing 8:20. After what time, the minute hand and hour hand will be making an angle of (90^\circ)?\

  1. $8: 30 \frac{10}{11}$
  2. $8: 32 \frac{9}{11}$
  3. $8: 27 \frac{3}{11}$
  4. $8: 12 \frac{9}{11}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

At 8:20, hour hand is at 250° (8×30 + 20×0.5), minute hand at 120° (20×6). Angle between them = 130°. To reach 90° separation, minute hand must gain 40° relative to hour hand. Relative speed = 5.5°/min. Time needed = 40/5.5 = 7 4/11 minutes. So 8:20 + 7 4/11 = 8:27 3/11. Option C is correct.

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