In a certain large company, the ratio of college graduates with a grad

It took me a while to see there are, indeed, 3 types of worker.
Let A = # of college graduates with a graduate degree
Let B = # of non-college graduates
Let C = # of college graduates without a graduate degree

Given: A : B = 1 : 8
Given: C : B = 2 : 3

Since both ratios share B, we need to create equivalent fractions that have the same value for B.
A : B = 1 : 8 = 3 : 24
C : B = 2 : 3 = 16 : 24

So, A : B : C = 3 : 24 : 16
3 + 24 + 16 = 43

So, for every 43 workers, there are:
- 3 college graduates with a graduate degree
- 24 non-college graduates
- 16 of college graduates without a graduate degree

If one picks a random college graduate at this large company, what is the probability this college graduate has a graduate degree?
We are picking a college graduate.
From the above info, we ignore the number of non-college graduates.
So, for every 19 college graduates, 3 have a graduate degree and 16 do not.

P(this college graduate has a graduate degree) = 3/19

Answer: D

Cheers,
Brent