Hypothesis testing — practice question

The lengths, in centimetres, of worms of a particular species are normally distributed with mean $\mu$ and standard deviation $2.3$. A magazine article gives the value of $\mu$ as $12.7$. A scientist wants to check whether this value is correct. He measures the lengths, $x$ cm, of a random sample of 50 worms of this species and obtains $\Sigma x = 597.1$. He intends to carry out a test, at the $1\%$ significance level, to find whether the true value of $\mu$ differs from $12.7$.