Question

For this problem, carry at least four digits after the decimal in your calculations. Answers may vary slightly due to rounding. A random sample of 5120 permanent dwellings on an entire reservation showed that 1697 were traditional hogans.

(a) Let p be the proportion of all permanent dwellings on the entire reservation that are traditional hogans. Find a point estimate for p. (Round your answer to four decimal places.)

(b) Find a 99% confidence interval for p. (Round your answer to three decimal places.)

lower limit

upper limit

Give a brief interpretation of the confidence interval.

Give a brief interpretation of the confidence interval.

1% of the confidence intervals created using this method would include the true proportion of traditional hogans.

99% of all confidence intervals would include the true proportion of traditional hogans.    

1% of all confidence intervals would include the true proportion of traditional hogans.

99% of the confidence intervals created using this method would include the true proportion of traditional hogans.

(c) Do you think that np > 5 and nq > 5 are satisfied for this problem? Explain why this would be an important consideration.

Yes, the conditions are satisfied. This is important because it allows us to say that p̂ is approximately normal.

No, the conditions are not satisfied. This is important because it allows us to say that p̂ is approximately normal.

Yes, the conditions are satisfied. This is important because it allows us to say that p̂ is approximately binomial.

No, the conditions are not satisfied. This is important because it allows us to say that p̂ is approximately binomial.

Answer 1

a) = 1697/5120 = 0.3314

b) At 99% confidence interval the critical value is z_0.005 = 2.58

The 99% confidence interval for p is

+/- z_0.005 * sqrt((1 - )/n)

= 0.3314 +/- 2.58 * sqrt(0.3314(1 - 0.3314)/5120)

= 0.3314 +/- 0.0170

= 0.3144, 0.3484

= 0.314, 0.348

Lower limit = 0.314

Upper limit = 0.348

99% of all confidence intervals would include the true proportion of traditional hogans.

c) np = 5120 * 0.3314 = 1696.768

    nq = 5120 * (1 - 0.3314) = 3423.232

Yes, the conditions are satisfied. This is important because it allows us to say that is approximately normal.