Answer & Explanation:
a) Total ways to select 4 cards out of 52
= 52 C 4 = 270725
Total ways to select 4 cards out of 40 other (faceless) cards
= 40 C 4 = 91390
P( faceless cards ) = 91390 / 270725
= 0.3376
P( minimum 1 face ) = 1 - P( faceless cards )
= 1 - 0.3376
= 0.6624
You should take the bet because probability of winning is greater than 50%.
b) Total ways to select 3 cards out of 52
= 52 C 3 = 22100
Total ways to select 4 cards out of 40 other (faceless) cards
= 40 C 3 = 9880
P( faceless cards ) = 9880 / 22100
= 0.4471
P( minimum 1 face ) = 1 - P( faceless cards )
= 1 - 0.4471
= 0.5529
You should take the bet because probability of winning is greater than 50%.