Question

Assume a family is planning to have three children.

A. What is is the probablity of a family having 2 girls.

B. The probablity of a family having at least 1 boy.


C. List the sample space using a B for Boy and G for girl (Hint there should be 8 possible outcomes).

Answer 1

a) prob (2 girls out of 3) = C(3,2) (1/2)^2 (1/2)
= 3(1/8) = 3/8

b) at least 1 boy --- no "all girls"

prob (all girls) = 1/8
prob (at least 1 boy) = 1 - 1/8 = 7/8

c)

BBB
BBG
BGB
GBB
GGB
GBG
BGG
GGG