2015 · Q31
A light was seen regularly at an interval of 13 seconds. It was seen for the first time at 1 hour 54 minutes 50 seconds (a.m.) and the last time at 3 hours 17 minutes 49 seconds (a.m.). How many times was the light seen?
Elementary MathematicsTime, Speed and Distance
- A375
- B378
- C383
- D384
Explanation
Elapsed time = 1 h 22 m 59 s = 4979 s; 4979/13 = 383 intervals, so the light was seen 383 + 1 = 384 times (option D).