alpha is (2/7)(1/6)=1/21

you can also do this by the hypergeo formula, but here we have to pick 2 red from a bowl with 2 reds and 5 blues.

You reach in and select a red with prob 2/7 and you DO NOT replace it.

Then there is 1 red left and still 5 whites, which has a 1/6 chance of being a red marble.