Question

A 95% confidence interval estimate of the population proportion p is .405<p<.455

a. What is the confidence interval?

b. what is a?

c. What is the critical value?

d. what is the point estimate?

e.What is the margin of error?

Answer 1

solution:

a.

the confidence interval lies between sample proportion

lower bound and upper bound .405<p<.455

b.

lower confidence interval 0.405

upper confidence interval0.455

0.405<sample peoprtion<0.455

c.

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z0.025 = 1.96   ( Using z table )

d.

Solution :

Point estimate = = (Lower confidence interval + Upper confidence interval ) / 2

Point estimate = = (0.405+0.455) / 2=0.43

Margin of error = E = Upper confidence interval - = 0.455-0.43=0.025