Question

A 2004 Gallup survey interviewed a nationally representative random sample of 550 teenagers aged 13 to 17; 60 acknowledged having smoked in the past week.

(b) Give the numerical value of the point estimate for this parameter.
(Use 3 decimal places)

(c) Calculate a 95% confidence interval for the parameter.
(  ,  ) (Use 3 decimal places)

Answer 1

Given that

random sample size=n= 550

X= 60

b) point estimate =sample mean =60/550 =0.1091

c) 95% Confidence level =critical value=1.96

for std error =(p(1-p)/n)^1/2 =0.0133

confidence interval =(sample mean -z*std error ; sample mean +z*std error )

                                     =(0.083 ;0.135)