So I want to say "from an hour to an hour and a half".
I figure this should work:
"de una hora a una hora y una media"
I've been googling around and there isn't much depth discussion on this sort of expression. When I threw this phrase into an online spanish checker, it told me that I should remove the una before media.
Depending on the context I would say:
De hora a hora y media.
Entre hora y hora y media.
When you have one as the minimum of your time range and no more than two as the maximum, you can omit that in Spanish.
De hora a hora y media.
De una hora a dos horas y media.
But, on the other hand, when you have a different minimum, you can omit the time "unit":
De tres a tres horas y media.
De diez a veinte años.
munchschair, you are confused with "una".
"Una" can be omitted or used before "hora" in any case.
If you think that "hora" is singular and "una" would force you to use "hora" in singular you know that "una" can be omitted if you want, so you can say
Una hora y media.
hora y media.
If you want to express a range of time the more used expressions arede/a, desde/hasta o entre/y like these:
Tengo de una hora a hora y media para llegar.
Para resolver el examen generalmente nos dan desde una hora hasta hora y media.
Para resolver el examen generalmente nos dan entre una hora y hora y media.
In all these examples you can omit "una"
For plural obviously you have to use the quantity and the plural "horas". For the same previous 3 examples we have.
.....de dos a tres horas....
.....de dos horas a tres.....
....desde dos hasta tres horas
...... desde dos horas hasta tres
.....entre dos horas y tres
.....entre dos y tres horas
In all these you can add "y media". i.e "dos horas y media"
What is wrong in your question is "una media". You should say "hora y media" "dos horas y media" or even "hora y cuarto" but never "dos horas y una media"
BTW. You could also move the placement of "horas". It is also valid to say "tengo dos y media horas para hacer la tarea"
