What is the correct use?
15 minutes are enough?
15 minutes is enough?
When you refer to a "chunk" of time, distance, weight, etc., you can use the plural.
Two miles isn't too far to walk.
Fifteen minutes is too long to wait.
Ten pounds is a good target for your weight loss.
It would be incorrect to say "one minute are."
It doesn't matter whether it is 1 minute or 10 minutes. It's the duration or span of time and that is singular.
It doesn't matter whether it is 1 kg or 10 kg. You are talking about the weight.
For example you don't say: '50 kgs are my weight.'
not a teacher
When we refer to an AMOUNT of money, time, weight, distance, or speed, we use of singular verb:
A thousand dollars is a lot of money.
Two hours is plenty of time to get to the airport.
Two kilos of grapes is enough for 4 people.
A million miles is just too far to walk even for one of your smiles.
40 m.p.h. is over the speed limit.