I need to find the weights of the market portfolio with three risky securities given the following information:
$\mu_1=0.08$
$\sigma_{1}^{2}=0.0255$
$c_{12}=0.00225$
$\mu_2=0.1$
$\sigma_{2}^{2}=0.0025$
$c_{13}=-0.0036$
$\mu_3=0.06$
$\sigma_{3}^{2}=0.0144$
$c_{23}=0 \\$
My textbook tells me to use the following formula to find the weights of market portfolio $$w_m=\frac{(m-Ru)C^{-1}}{(m-Ru)C^{-1}u^T}$$
where $m$ is the expected return matrix, $R$ is the risk-free return rate, $5\%$ in this example, $u$ is just the matrix $[1 \quad 1 \quad 1]$ and $C^{-1}$ is the inverse of the covariance matrix that is created using the variance and covariances of the securities.
I have tried to do this twice, once on excel and I keep getting the weights $w=[-0.04477 \quad 1.02203 \quad 0.02274]$ but the answer key says the weights are $w=[0.438 \quad 0.012 \quad 0.55]$
does anyone know if this is the correct formula or if I am doing something wrong? All those numbers are correct and I know how to multiply matrices.