A factory whistle blows every 30 minutes. The clock tower chimes every 15 minutes. If they both sounded at 1:00 p. M.,at what time will you hear them both at the same time again?

1.30 p.M.

Step-by-step explanation:

The factory whistle blowed at 1:00 p.M, and it blows every 30 minutes, so it will blow again at 1:30 p.M.

The clock tower chimed at 1.00 p.M., and it chimes every 15 minutes, so it will chime again at 1:15 p.M, and after that, it will chime again at 1:30 p.M.

So, you will hear them both at the same time at 1:30 p.M.

We can also solve this problem using LCM:

the least commom multiple between 15 and 30 is 30, so we just need to sum 30 to the inicial time (1:00 p.M.), so the time they will "find each other" again is 1.30 p.M.

25% is the answer