Can some one help me and explain me how to resolve the folowing question ?

A stable, normally distributed process with specification 3,50 ± 0,03 has μ = 3,51
and σ = 0,016. What percent of the production violates specification?

Answer should be 11.18 %
How to get this ?
How do you compute the probability that the normally distributed random variable will be below the lower specification limit?

(Let's additionally assume that they are statistically independent.)