Posted by **Kayla** on Sunday, February 10, 2013 at 4:28pm.

If the probability of a newborn child being female is 0.5, find the probability that in 100 births, 55 or more will be female. Use the normal distribution to approximate the binomial distribution.

- Statistics -
**MathGuru**, Sunday, February 10, 2013 at 5:45pm
Mean = np

Standard deviation = √npq

Note: q = 1 - p

n = 100

p = 0.5

q = 0.5

Once you find the mean and standard deviation, use z-scores:

z = (x - mean)/sd

(x = 55)

Check a z-table to find the probability using the z-score you calculated.

- Statistics -
**Jane**, Sunday, February 10, 2013 at 6:35pm
54.5-50/50 = 4.5/5 = 0.9 z= 0.1841

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