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The traffic lights at four different road crossings change after every 15 sec, 18 sec, 27 sec and 30 sec respectively. If they all change s…

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The traffic lights at four different road crossings change after every 15 sec, 18 sec, 27 sec and 30 sec respectively. If they all change simultaneously at 6 : 10 : 00 hours, then at what time will they again change simultaneously?
  • A6 : 14 : 30 hours
  • B6 : 40 : 00 hours
  • C6 : 14 : 00 hours
  • D10 : 40 : 00 hours
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CCommunity
LCM of 15 sec, 18 sec, 27 sec, 30 sec = 2 × 3 × 3 × 5 × 1 × 1 × 3 × 1 = 270 sec

270 sec = 270/60 = 4 min 30 sec = 0 : 04 : 30

∴ They will again change simultaneously at 6 : 10 : 00 + 0 : 04 : 30 = 6 : 14 : 30 hours
0
CCommunity
LCM of 15 sec, 18 sec, 27 sec, 30 sec = 2 × 3 × 3 × 5 × 1 × 1 × 3 × 1 = 270 sec

270 sec = 270/60 = 4 min 30 sec = 0 : 04 : 30

∴ They will again change simultaneously at 6 : 10 : 00 + 0 : 04 : 30 = 6 : 14 : 30 hours