It can even be 50:50. I mean if she lose, I will give her 50% of her loss back but if she make profit she will give me 50% of her profit.
But what I have told people that say something like this is that they should not invest if they can not take the risk.
First you're suppose to tell her the risk that is involve,that is why she need to have the full knowledge of investment before looking out to any other thing, I guess she don't have any idea about investment that is why she's being scared of losing her money, i think if she's not ready to take the risky I will advice you just let her be.