Binomial distribution and probability problem

[the_d]

Homework Statement

A population has an average of 12 defects per 100 feet of wire sampled and inspected. What is the probability of finding 20 or fewer defects in a sample?

Homework Equations

I think I am supposed to use the binomial distribution b(x;n,p)

The Attempt at a Solution

Where should i look to start?

 

[statdad]

If you want to use the binomial distribution you need a sample size, do you not? You don't have one here.
What distribution do you know of that refers to the mean number of items per (area, length, volume, time)?