Q1) A current study of 750 Internet users in Europe found that 35% of Internet users were women.  Determine the 95% confidence interval estimate for true proportion of women in Europe who use Internet?

a) 0.321 < p < 0.379

b) 0.316 < p < 0.384

c) 0.309 < p < 0.391

d) 0.305 < p < 0.395

Q2) A researcher wants to know, with 98% confidence, percentage of women who wear shoes that are too small for their feet.  A earlier study conducted by Academy of Orthopedic Surgeons determined that 80% of women wear shoes that are too small for their feet.  If researcher wishes her estimate to be within 3% of true proportion, how large a sample is essential?

 a) 966

b) 683

c) 183

d) 484

Q3) 25 volunteers who had developed cold symptoms within last 24 hours were given zinc lozenges to take every 2 to 3 hours until their cold symptoms were gone. Mean overall duration of symptoms was 4.5 days with standard deviation of 1.6 days.

Selected cases have distribution that appears to be symmetric and bell-shaped.

1) Create a 99% confidence interval for mean overall duration of symptoms in population of individuals who used zinc lozenges.

2) In earlier test, mean overall duration of symptoms for volunteers who were told to drink herbal tea for relief of their symptoms was 7 days. Based on your confidence interval, do you believe that using lozenges reduces overall duration of symptoms compared to using herbal tea?