In a small town,it is known that 20% of the families have no children. 30% have 1 child, 20% have two children, 16 % have three children, 8 % have 4 children, and 6 % have five or more children. find the probability that the family has more than 2 children if it is known that it has atleast 1 child. Please help me :(

Question

In a small town,it is known that 20% of the families have no children. 30% have 1 child, 20% have two children, 16 % have three children,  8 % have 4 children, and 6 % have five or more children. find the probability that the family has  more than 2 children if it is known that it has atleast 1 child. Please help me :(

waleed_imtiaz · Answer

@quickstudent

mhchen · Answer

I think you add the percentages of 3-children and up.
16% + 8% + 6%

waleed_imtiaz · Answer

after that? how to calculate probability?

nurali · Answer

This is the Conditional Probability Problem.

nurali · Answer

You need to find the of having more than 2 children given that there is at least one child or P(X≥2| X≥1). For this we use Bayes' Theorem. X is the number of children in the family.

nurali · Answer

P(X>2|X≥1) = [P(X≥1|X>2)*P(X>2)]/P(X≥1)

waleed_imtiaz · Answer

how to solve furthur ? @Nurali

waleed_imtiaz · Answer

isn't this is the formula? 
P(A|B) = P(A intersection B)/P(B) ???

waleed_imtiaz · Answer

@zepdrix

waleed_imtiaz · Answer

@ganeshie8