For a normal distribution, with a mean of $\displaystyle 10.5$ and a variance of $\displaystyle 16.7$, determine the value of $\displaystyle X_{0}$ so that $\displaystyle P(10.5 < x < X_{0}) = 0.4987$.

I am very lost on this question, any and all help is greatly appreciated!

Answer is supposedly $\displaystyle X_{0}=22.76$