Question 842528
Given that a collection has 13 cards and no of ways selecting 7 cards is 13C7.
i.e., 858
no of ways selecting 4 birthday cards from 8 is 8C4 = 70
no of ways selecting 3 thank you cards  from 5 is 5C3 = 10
Probability of selecting 4 birth day card and 3 thank you card is = 70*10/858