Power of Poisson likelihood ratio test

Let $X_1, X_2, X_3, X_4$ be a random sample from a Poisson distribution with unknown mean $\lambda > 0$. For testing the hypothesis $H_0: \lambda=1$ against $H_1: \lambda=1.5$, let $\beta$ denote the power of the test that rejects $H_0$ if and only if $\sum_{i=1}^4 X_i \ge 5$. Then which one of the following statements is true?