In: Statistics and Probability
In a recent survey of 200 Instagram users, it was found that 71% of them were under the age of 35. Create and interpret a 95% Confidence Interval for the percentage of Instagram under the age of 35 using PANIC.
Solution :
Given that,
n =200
Point estimate = sample proportion =
= 0.71
1 -
= 1- 0.71 =0.29
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 )
Margin of error = E = Z
/ 2 *
(((
* (1 -
)) / n)
= 1.96 (((0.71*0.29)
/200 )
= 0.0629
A 95% confidence interval for population proportion p is ,
- E < p <
+ E
0.71-0.0629 < p <0.71+ 0.0629
0.6471< p < 0.7729
The 95% confidence interval for the population proportion p is : 0.6471, 0.7729