Question

why do we use lcm for this qn... I need correct explanation ​

Answer 1

Answer:

To find a value that both device make beep at same time.

Step-by-step explanation:

Answer 2

Answer:

We use L.C.M. because we need to find out the lowest time after which they will beep together.

L.C.M. is the lowest number which is the common multiple of the numbers or which comes in the table of both numbers. Here the thing we have to find is the minimum time after which both of them will beep together i.e. the common number coming in the table of both numbers and L.C.M. is this number.

If you have confusing in deciding what to find, you can use a trick. If words like lowest, smallest, earliest, minimum etc are used then you have to find L.C.M., and if words like highest, biggest, maximum, largest etc are used, then find the H.C.F.