Let \(X_1,\ldots ,X_n\) be a random sample with density function \(f(x)=2e^{-2(x-\eta )}\) for \(x>\eta \), and zero otherwise. We wish to test \(H_0:\eta =4\) versus the alternative \(H_A:\eta >4\). We reject \(H_0\) if \(X_{(1)}=\min _{1\leq i\leq n}X_i\geq 4+2/n\).
(a) Compute the significance level of the test.
(b) Compute the power function.