A clock is 4 minutes slow at 8:20 AM and 8 minutes fast at 2:50 PM. At what time (in AM) will it show the correct time?
Show answer & explanation
Correct answer: B
Explanation
Initial error = –4 minutes
Final error = +8 minutes
Total change = 4 + 8 = 12 minutes
Time interval:
Duration from 8:20 to 2:50:
8:20 → 14:50
= 6 hours 30 minutes = 390 minutes
The clock will move from –4 to 0.
This represents 4/12 = 1/3 of the total change.
Calculate the time elapsed:
390 × (1/3) = 130 minutes = 2 hours 10 minutes
Final time:
8:20 + 2:10 = 10:30
Option B is correct.