How many 15 seconds are there in 5 minutes?

Answer 1

1 minute = 60 seconds = 60/15 = 4 lots of 15 second timeslots.

So

5 minutes = 5*4 = 20 such intervals.

another way of looking at it :

a 15 second timeslot can start anywhere, as long as it will have 15 seconds in it

so within 15 seconds that will be one slot, obvious

within 16 seconds there will be 2 slots, one start at the first second, second one starting at the second second.

so for 5 minutes, which equals 300 seconds, that would amount to 286 slots.