# SOLUTION: Three lighthouses on three nearby islands flash their lights every evening beginning at 8:35pm. On one island, the ligh flashes every 45 seconds. The lighthouse on the second isl

Algebra ->  Algebra  -> Human-and-algebraic-language -> SOLUTION: Three lighthouses on three nearby islands flash their lights every evening beginning at 8:35pm. On one island, the ligh flashes every 45 seconds. The lighthouse on the second isl      Log On

 Ad: Algebra Solved!™: algebra software solves algebra homework problems with step-by-step help! Ad: Algebrator™ solves your algebra problems and provides step-by-step explanations!

 Word Problems: Translating English into Algebreze Solvers Lessons Answers archive Quiz In Depth

 Click here to see ALL problems on Human-and-algebraic-language Question 166271: Three lighthouses on three nearby islands flash their lights every evening beginning at 8:35pm. On one island, the ligh flashes every 45 seconds. The lighthouse on the second island has a light that flashes every 2 minutes. The third lighthouse flashes a light every 1 1/4 minutes. At what time will all three lights flash together again? This is a problem of the week just given to my child on a single piece of paper. Found 3 solutions by checkley77, scott8148, ankor@dixie-net.com:Answer by checkley77(12569)   (Show Source): You can put this solution on YOUR website!FACTORING EACH OPF THE TIMES IN MINUTES WE THEN FIND THE LOWEST COMMON DENOMINATOR. 45=2*2*2*5 120=2*2*2*3*5 75=3*5*5 NOW WE HAVE 2*2*2*3*5*5=600 MINUTES AFTER 8:35 THEY WILL ALL FLASH. 600MIN.=10 HOURS. THUS THE TIME WILL BE 8:35 PM+10:00=6:35 AM. Answer by scott8148(6628)   (Show Source): You can put this solution on YOUR website!you are looking for the lowest common multiple 45sec = 3 * 15 2min = 120sec = 8 * 15 1 1/4 min = 75sec = 5 * 15 LCM = 15 * 3 * 8 * 5 = 1800sec = 30min so, every half hour they flash together Answer by ankor@dixie-net.com(15647)   (Show Source): You can put this solution on YOUR website!Three lighthouses on three nearby islands flash their lights every evening beginning at 8:35pm. On one island, the ligh flashes every 45 seconds. The lighthouse on the second island has a light that flashes every 2 minutes. The third lighthouse flashes a light every 1 1/4 minutes. At what time will all three lights flash together again? : Convert 2 min to seconds and 1.25 min to seconds. : So we have: : Lt1 = 45; Lt2 = 120; Lt3 = 75 : Prime factor each: 45: 3,3,5, 120: 2,2,2,3,5 75: 3,5,5 : Lcm of all three: 2,2,2,3,3,5,5 Multiply this: 1800 secs they will all Flash : 1800/60 = 30 min: At 9:05Pm this should occur