Question

Three bells ring at interval of $7,10$ and $14$ minutes respectively. They begin by ringing together. After how long will they ring together again?

Answer 1

Three bells $7,10,14$ minutes

They will be ringing after L.C.M of $(7,10,14)$ minutes

Factorise $7,10,14$

$7=7$

$10=5\times 2$

$14=7\times 2$

$\Rightarrow$ L.C.M $(7,10,14)=7\times 2\times 5=70$

$\therefore$ They will be ringing together after $70$ minutes.