               
                  <h1>Ex. 15.7</h1>
                
                <details class="question" open="open"><summary>Ex. 15.7</summary><p>Suppose we fit a linear regression model to <span class="arithmatex">\(N\)</span> observations with response <span class="arithmatex">\(y_i\)</span> and predictors <span class="arithmatex">\(x_{i1}, ..., x_{ip}\)</span>. Assume that all variables are standardized to have mean zero and standard deviation one. Let <span class="arithmatex">\(RSS\)</span> be th