alleryThree lights change every 48 s, 72 s and 108 s. After how many seconds do they change together again?
A324
B864
C432
D216
Answer & Solution
Correct answer: C. 432
48 = 2^4 x 3, 72 = 2^3 x 3^2, 108 = 2^2 x 3^3, so the LCM is 2^4 x 3^3 = 432.
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