Respuesta :
Answer: (0.2659, 0.4541)
This is the same as saying 0.2659 < p < 0.4541
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Work Shown:
At 95% confidence, the z critical value is about z = 1.96 which is determined through a table or calculator.
x = number of people who had kids = 36
n = sample size = 100
phat = sample proportion of those who had kids
phat = x/n
phat = 36/100
phat = 0.36
E = margin of error
E = z*sqrt(phat*(1-phat)/n)
E = 1.96*sqrt(0.36*(1-0.36)/100)
E = 0.09408
This value of E is approximate because z = 1.96 is approximate.
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L = lower bound
L = phat - E
L = 0.36 - 0.09408
L = 0.26592
L = 0.2659
U = upper bound
U = phat + E
U = 0.36 + 0.09408
U = 0.45408
U = 0.4541
The values of L and U are approximate since E is approximate.
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The confidence interval in the format (L, U) is (0.2659, 0.4541)
This is equivalent to writing 0.2659 < p < 0.4541
which is the format L < p < U
We're 95% confident that the true population proportion (p) is somewhere between 0.2659 and 0.4541; i.e. we're 95% confident the true percentage of people who had kids is somewhere between 26.59% and 45.41%
