The pattern is increasing by 10 then a ding 1 to the next number. Hope this helps! :)
The vertex is (-1, 2).
The equation of parabola:
where (h, k) is the vertex
We have h = -1 and k = 2.
Substitute:

So if it’s 2/12 it would be 1 flaw in every 6 light bulbs. so if there were 18 light bulbs there would be 3 flaws (6 * 3 is 18)
It’s the 3 and for number 2 it’s 1