In a random sample of 120 cigarette smokers who were assigned to use vaporizer, 34 reported that they quit smoking after 10 weeks.
a) Give a point estimate, ?′, for the proportion of cigarette smokers who quit smoking after 10 weeks of using vaporizer
b) Construct a 99% confidence interval for the point estimate you determined in part a.
Solution :
Given that,
Point estimate = sample proportion = = x / n = 34 / 120 = 0.283
Z/2 = 2.576
Margin of error = E = Z / 2 * (( * (1 - )) / n)
= 2.576 * (((0.283 * 0.717) / 120)
= 0.106
A 99% confidence interval for population proportion p is ,
- E < p < + E
0.283 - 0.177 < p < 0.283 + 0.177
0.177 < p < 0.389
(0.177 , 0.389)
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