How to calculate the optimal weight of a T-bill in a portfolio consisting of 10 stocks and 1 T-Bill?

I have to create a portfolio consisting 10 stocks( random) plus 1 t bill. I was able to do almost all the work and find the optimal weight of the risky portfolio which came out to be 418.38%. not sure if this is correct but I'm not sure how to calculate optimal weight of the tbill in the portfolio. I think it should be 1-418.38% but not sure. please help. thanks