Multiple choice

A clock was set correctly at 12:00 noon. It gains 10 minutes every hour. Later, the same clock shows 3:00 PM. What is the correct actual time then?

  1. 2:48:00 PM

  2. 2:34:17 PM

  3. 2:45:00 PM

  4. 2:50:00 PM
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The clock gains 10 minutes every hour, meaning it shows 70 minutes for every 60 minutes of real time. Ratio = 7/6. The clock shows 3 hours passed (12:00 to 3:00). Actual time passed = 3 * (6/7) = 18/7 hours = 2 hours and 34.28 minutes. 2 hours 34 minutes and 17 seconds.

AI explanation

Using the proportion method for faulty clocks, we find the actual time elapsed based on the time shown by the fast clock. The clock shows 3 hours (180 minutes), and for every 70 actual minutes it advances 70 minutes, so the actual time elapsed is 180 multiplied by 60 divided by 70, which is 154 and 2/7 minutes (2 hours, 34 minutes, and approximately 17 seconds). The correct actual time is therefore 2:34:17 PM.

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