Posted by **sam** on Saturday, April 21, 2012 at 6:02pm.

A random sample of n=500 households in a certain metropolitan area revealed that 150 have combined cable, phone and internet service.

a.Calculate p-hat, the sample proportion of households having such service.

b.Calculate a confidence interval for π, the proportion of all households in this area that have such service; use a confidence level of 90%.

- Stats -
**MathGuru**, Saturday, April 21, 2012 at 7:09pm
For a): p-hat = x/n = 150/500 (convert to a decimal to use in part b).

For b): CI90 = p ± (1.645)[√(pq/n)]

...where p = x/n, q = 1 - p, and n = sample size.

Note: ± 1.645 represents 90% confidence interval.

Hopefully, you can take it from here.

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