Mathematics for IGCSE & O level - Number (Section 3 - No. 17)
What is the next time that the lights flash at the same time if the lights flash every 22 and 16 seconds respectively? Both lights switched on at 10 p.m.
10:04:20 p.m.
10:04:48 p.m.
10:05:00 p.m.
10:05:12 p.m.
Explanation
Find the LCM of 22 and 16, which is 176. Then, divide 176 by 60 to get the number of minutes (2.93). Multiply the fractional portion by 60 to get the number of seconds (56). The answer is 2 minutes and 56 seconds later.
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