I had an contest in Mathematics and I had a very unusual task from probability theory.

The task is the following:

“There are 8 black pencils and 12 pencils pens in the box.
We randomly pick out 2 pencils without putting back.
Calculate the Variance of taking out two BLACK pencils”.

Does anybody know the correct solution?

I used formulas from Binomial distribution:
p = 8/20 * 7/19
q = 1 – 8/20 * 7/19

Variance in Binomial distribution = npq
Variance = 2 * 8/20 * 7/19 * (1 – 8/20 * 7/19) ≈ 0,25

Is this an appropriate solution?