In: Statistics and Probability
In a survey of 3992 adults, 717 oppose allowing transgender students to use the bathrooms of the opposite biological sex. Construct a 99% confidence interval for the population proportion. Interpret the results.
A 99% confidence interval for the population proportion is (,)
Solution :
Given that,
n = 3992
x = 717
Point estimate = sample proportion =
= x / n = 717/3992=0.180
1 -
= 1 -0.180=0.820
At 99% confidence level the z is ,
= 1 - 99% = 1 - 0.99 =
0.01
/ 2 = 0.01 / 2 = 0.005
Z/2
= Z0.005 = 2.576 ( Using z table )
Margin of error = E = Z
/ 2 *
((
* (1 -
)) / n)
= 2.576 (((0.180*0.820)
/ 3992)
E = 0.0157
A 99% confidence interval for population proportion p is ,
- E < p <
+ E
0.180 -0.0157 < p <0.180+ 0.0157
0.1643< p < 0.1957
The 99% confidence interval for the population proportion p is : 0.1643, 0.1957