Question

On the coast there are three lighthouses.
The first light shines for 3 seconds, then is off for 3 seconds.
The second light shines for 4 seconds, then is off for 4 seconds. The third light shines for 5 seconds, then is off for 5 seconds.
All three lights have just come on together.

When is the first time all three lights will be off at the same time?
When is the next time all three lights will come on together at the same moment?

Your Videos by presh Talwalkar

Answer 1

Answer:

Both the timing is 60 seconds

Step-by-step explanation:

H.C.F of the no. remains same 3,4,5

So, after multiplying 3 x 4 x 5

=60 seconds

Given that their shining time and time closing is same so if we multiply their H.C.F=3 x 4 x 5

60 seconds later