In: Math
8.3 Is the environment a major issue with Americans? To answer that question, a researcher conducts a survey of 1255 randomly selected Americans. Suppose 707 of the sampled people replied that the environment is a major issue with them. Construct a 95% confidence interval to estimate the proportion of Americans who feel that the environment is a major issue with them. What is the point estimate of this proportion? Appendix A Statistical Tables
(Round the intermediate values to 3 decimal places. Round your answer to 3 decimal places.)
___________ ≤ p ≤ __________
The point estimate is _______.
Solution :
n =1255
x = 707
The point estimate is
= x / n = 707 / 1255 = 0.563
1 - = 1 - 0.563= 0.437
At 95% confidence level the z is ,
= 1 - 95% = 1 - 0.95 = 0.05
/ 2 = 0.05 / 2 = 0.025
Z/2 = Z0.025 = 1.960
Margin of error = E = Z / 2 * (( * (1 - )) / n)
= 1.960 * (((0.563 * 0.437) / 1255)
= 0.027
A 95 % confidence interval for population proportion p is ,
- E < P < + E
0.563 - 0.027 < p < 0.563 + 0.027
0.536 < p < 0.590