Probability That A Woman Will Give Birth, Word Problem

Oct 2011
66
2
The probability that a woman will give birth to a girl during any given pregnancy is 48%.


Please check answer to A.
a.) What is the probability that a couple planning to have four children will have exactly one girl?

P(x) = C(n,x) * P^x * Q^n-x
P(x) = C(4,1) * 0.48^1 * 0.52^3
P(x) = 0.27 ...(27%)


Need help with B.
b.) What is the probability that a couple planning to have five children will have at least two girls?

Do I solve this the same way as B, just changing 4 children to 5, and one girl to at least 2 girls? Which "formula" do I use and why? I'm really confused with this one.

 

Plato

MHF Helper
Aug 2006
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8,663
The probability that a woman will give birth to a girl during any given pregnancy is 48%.
Please check answer to A.
a.) What is the probability that a couple planning to have four children will have exactly one girl?
P(x) = C(n,x) * P^x * Q^n-x
P(x) = C(4,1) * 0.48^1 * 0.52^3
P(x) = 0.27 ...(27%)

Need help with B.
b.) What is the probability that a couple planning to have five children will have at least two girls?
I have not done the calculation, but the setup is correct for part a).

For part b) do it for exactly 2, 3, 4, & 5. Then add the results.