[Masquerade]

If you start with 3 there are 10 left out of 47. You must hit on both cards so 10/47 * 9/46 = 0.04+

If you start with 4 there are 9 left out of 47. You only need to hit at least once, or equivalently NOT miss twice. So chance is (1 - 38/47 * 37/46) = 0.35

Imagine 3,000,000 births. 3,000 will be fraternal twins (750 BB, 1,500 BG, 750 GG) and 2,000 will be identical twins (1,000 BB and 1,000 GG).

So chance that GG is fraternal is 3/7.