Multiple choice general knowledge math & puzzles

Three bells chime at an interval of 18, 24 and 32 minutes respectively. At a certain time they begin to chime together. What length of time will elapse before they chime together again?

  1. 2 hours 24 minutes

  2. 4 hours 48 minutes

  3. 1 hour 36 minutes

  4. 5 hours

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

The time until they chime together again is the Least Common Multiple (LCM) of 18, 24, and 32. 18=2*3^2, 24=2^3*3, 32=2^5. LCM = 2^5 * 3^2 = 32 * 9 = 288 minutes. 288 minutes is exactly 4 hours and 48 minutes.