Complete question :
Cyber Monday Shopping A survey of 1000 U.S. adults found that 33% of people said that they would get no work done on Cyber Monday since they would spend all day shopping online. Find the 95% confidence interval of the true proportion.
Answer:
(0.301 ; 0.359)
Step-by-step explanation:
Sample size, n = 1000
Phat = 0.33
(1 - phat) = 1 - 0.33 = 0.67
Zcritical at 95% = 1.96
Confidence interval :
Phat ± margin of error
Margin of Error = Zcritical * sqrt[(phat(1 - phat)) /n]
Margin of Error = 1.96 * sqrt[(0.33 * 0.67) / 1000]
Margin of Error = 1.96 * 0.0148694
Margin of Error = 0.0291440
Lower boundary = (0.33 - 0.0291440) = 0.300856
Upper boundary = (0.33 + 0.0291440) = 0.359144
(0.301 ; 0.359)
