Right age for a Guinea Pig?

[JD In Van]

My daughter's 9 which is I think a good age to add a pet to the house hold. With an average age of 5 - 6 the guinea pig's life span will mostly be within that period of time when she's about the hous and happy to spend time with pets.

But the pets are part of the house hold. She helps but ultimately I have to make sure they get everything they need. She gets the fun stuff (feeding them in the morning while I clean their pen for example).