Probability distribution question including mean and variance

Question

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.

Answer 1

Perhaps this figure will help:

In Mathematica:

1 - Integrate[
           PDF[NormalDistribution[118, 0.3], x], 
           {x, 117.11, 118.37}]

(* 0.110231 *)