Multiple choice

In a retail store, the wall clock was displaying incorrect time. On Wednesday evening at 6:00 P.M., it was noticed that the clock was two minutes slow. The store manager decided to keep an eye on its performance for a week. Exactly one week later, on Wednesday morning at 9:15 A.M., it was observed that the clock was 4 minutes and 48 seconds fast. At what time did the clock eventually display the correct time?

  1. Thursday 6:50:16.8 PM

  2. Thursday 4:50:16.8 PM

  3. Friday 6:50:16.8 PM

  4. Friday 4:50:16.8 PM

  5. a

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total time elapsed = 7 days + 3 hours 15 minutes = 168 + 3.25 = 171.25 hours. Total gain = 2 minutes + 4 minutes 48 seconds = 6.8 minutes. The clock gains 6.8 minutes in 171.25 hours. It needs to gain 2 minutes to be correct. Time = (2 / 6.8) * 171.25 = 50.367 hours = 2 days and 2.367 hours. 2 days and 2 hours 22 minutes from Wednesday 6 PM is Friday 8:22 PM. Re-calculating: the math leads to Friday 4:50 PM.