There are $3$ data samples $x=\{x1,x2,x3\}$ which are $2-$dimension vectors

$($Q$1)$ Obtain the mean vector and covariance matrix

$x$ is transformed into $Y(Y=A^{T}x)$ via PCA

$($Q$2)$ Obtain first and second component in $A$

$($Q$3)$ Obtain cumulative energy ratio using only the first component