Statistics
posted by Kayla on .
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.

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 zscores:
z = (x  mean)/sd
(x = 55)
Check a ztable to find the probability using the zscore you calculated. 
54.550/50 = 4.5/5 = 0.9 z= 0.1841