The lengths of the drive rods produced by a small engineering company are normally distributed with a mean of 118 cm and a standard deviation of $0.3\ cm$. Rods that have a length of more than $118.37\ cm$ or less than $117.11\ cm$ are rejected. Find the percentage of rods that are rejected.
This is a probability distribution question which I am stuck on. I don't know how to approach the question. I tried finding the value of $p$ by isolating it from the variance formula but I don't think that is the right approach for this question.