c) Find the Yule-Walker equation for the \( \mathrm{AR}(2) \) process \[ X_{t}=\frac{1}{3} X_{t-1}+\frac{2}{9} X_{t-2}+e_{t}, e_{t} \sim W N\left(0, \sigma_{e}^{2}\right) \]

The median of \( : a+2, a, a-2, a-1, a+1 \) is

What is a scatter plot?

A survey shows that \( 63 \% \) of the Americans like cheese whereas \( 76 \% \) like apples. If \( x \% \) of the Americans like both cheese and apples, then \( \begin{array}{ll}\text { (a) } x=39 & \text { (b) } x=63 \\ \text { (c) } 39 \leq x \leq 63 & \text { (d) None of these }\end{array} \)

What is a scatter plot?

Theorem : If \( Z \sim N(0,1) \) and \( U-x^{2}(v) \) and in addition, \( Z \) and \( U \) are independent, then the random variable \( W \) defined by \( W=\frac{Z}{\sqrt{\frac{U}{V}}} \) has a \( t \)-distribution with \( v \) degrees of freedom.