A family decides to have 20 children. Find the probability of:

a) no girls

b)exactly 19 boys

c)at least 1 girl

d) at most 1 boy

please help and show your work or atleast explain how i can arrive at the answer

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- Apr 28th 2010, 02:34 PMdrewbearchild probability
A family decides to have 20 children. Find the probability of:

a) no girls

b)exactly 19 boys

c)at least 1 girl

d) at most 1 boy

please help and show your work or atleast explain how i can arrive at the answer

- Apr 28th 2010, 03:05 PMpickslides
Lets

**assume**X~Binomial(n=no of trials, p= probability of success)

The binomial theorem states

In your case lets call X the probability of having a girl with and

a) find

b) exactly 19 boys = exactly 1 girl so find

c) "at least 1" means 1 or more so find

Remember

d) "at most 1" means 1 or less so this means 2 or more girls now find