Four traffic lights along a street turn red at regular intervals of 1 minute,1 minute 10 seconds,1 minute 18 seconds and 1 minute 31 seconds respectively.Occasionally all four traffic lights will turn red simultaneously.If all traffic lights turned red simultaneously at 0830,find the next time it occurs again.
1 min=60 secs
1 min 10 secs=70 secs
1 min 18 secs=78 secs
1 min 31 secs=91 secs
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Karry
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2Welcome to MathSE. Please note that this is not a HW site. Please identify what you don't understand and/or share some of your own thoughts. – Rumplestillskin Jun 19 '17 at 07:57
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You are just asking the least common multiple of the set $$ \{60,70,78,91\}\,\,\text{(seconds.)} $$
Paolo Leonetti
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