A survey of 800 women shoppers found that 17% of them shop on impulse. What is the 98% confidence interval for the true proportion of women shoppers who shop on impulse?

Question

Quizplus · Accepted Answer

We can use the formula for the confidence interval for a proportion:
p ± z*sqrt((p*(1-p))/n)
where p is the sample proportion, z* is the z-score corresponding to the level of confidence (in this case 2.33 for 98%), and n is the sample size.

Plugging in the values, we get:
0.17 ± 2.33*sqrt((0.17*(1-0.17))/800)

Calculating this out, we get the confidence interval of (0.135, 0.205), which corresponds to option C.

A Survey of 800 Women Shoppers Found That 17% of Them