Answer to Question #142392 in Statistics and Probability for victory

Question

Theorems of addition of probability and theorems of multiplication of probabilities are used for solving
1. What is the probability of drawing either a king or a queen in a single drawing from a deck of 52 playing cards?
2. There are 3 children in family. The birth o a girl and a boy is considered to be
equally possible. Find out the probability of the fact that all children in the family
are boys.

Answer 1

1) P(drawing either a king or a queen) = P(drawing a king) + P(drawing a queen) =

$=\frac{4}{52}+\frac{4}{52}=\frac{8}{52}=\frac{2}{13}=0.15$

2) P(3 children are boys):

P(1st child is a boy) * P(2nd child is a boy) * P(3rd child is a boy)=$\frac{1}{2}\cdot\frac{1}{2}\cdot\frac{1}{2}=\frac{1}{8}=0.125$