November 20, 2009
Three lighthouses are visible from the promenade at Rivermouth. One flashes every 1½ minutes, another?
debanjanghosh_prantik asked:
Three lighthouses are visible from the promenade at Rivermouth. One flashes every 1½ minutes, another flashes every 2 minutes, and the third flashes every 50 seconds.
Three lighthouses are visible from the promenade at Rivermouth. One flashes every 1½ minutes, another flashes every 2 minutes, and the third flashes every 50 seconds.
All three have just flashed at the same time.
How long will it be before they all flash at the same time again?
The options are - 6, 10 ,7.5 , 30, 150 mins
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Comments on Three lighthouses are visible from the promenade at Rivermouth. One flashes every 1½ minutes, another? »
For this question and always ready to help you when ever you but this question and always ready to help you require such help.
the ans is 30 min.
since all of them have to flash at one given time , that time should be in ratio with all the indidual timings of lights.
so the l.c.m of 90, 120,50=1800sec=30 min.
find LCM of 3/2, 2 and 5/6.
answer = 30 minutes.
The lowest of 90 120 3rd 50 which is multiple choice question you have multiple choice question you have multiple of these that multiplies by these there is multiple of 90 2nd 120 3rd 50 you need to doing this but.
For 90 sec 30 minutes.
For 90 sec 2nd lighthouse 50 sec 30 minutes.