Afew years ago, european medical researchers concluded a study of whether hiv is transmitted by infected mothers to infants via breast milk. the study included 721 babies born to hiv-positive mothers between december 1984 and august 1991 in 19 cities in germany, italy, the united kingdom, spain, the netherlands, sweden, and belgium. 385 of these mothers breast-fed their infants and 75 of their infants became infected by eighteen months of age. 336 mothers bottle-fed their infants, and 29 of these infants became infected by eighteen months of age. using the confidence interval approach, test the null hypothesis that among babies born to hiv-positive mothers, the proportions infected were the same for breast-fed babies (x population) and bottle-fed babies (y population), against the alternative that these proportions are different. use a 1% level of significance.

what are the correct null and alternative hypotheses? which is the correct test statistic to use as the basis for the relevant confidence interval? what is the upper end of the confidence interval? what is the conclusion of the test?

Onsider the following subscription behavior information from genie, a web site that provides tools for constructing a family tree (ancestor search). subscriptions cost $9.99 per month, but you are charged for the entire year at the time of purchase. there is a one-year minimum term when you sign up for the service. once purchased, subscriptions are set to renew automatically unless the subscriber cancels them. when a membership renews, it renews for a one-year term and again you are charged for the entire year. there are no variable costs associated with providing this service to an individual customer, but genie does engage in customer relationship activities that they believe will increase customer retention. these customer relationship activities cost genie about $10 per year per customer. based on a sample of 1000 customers that joined genie five years ago, near the time when the company was founded, they were able to determine how many of those customers remained subscribers in the second year, third year etc. based on this information, genie calculated the average annual retention rate to be 20%. genie uses an annual discount rate of 8%. a. last year, genie spent $10,000 placing advertisements on google. genie management believes that these advertisements were responsible for about 300 new subscribers. would you recommend to genie management that they purchase more google ads? b. suppose a newly-introduced loyalty program increases the number of customers that remained to 30%. does this new data change your answer to 9.a? c. do you have any hesitations or concerns about making recommendations to management based on your above estimate of customer lifetime value?

After graduation, you plan to work for dynamo corporation for 12 years and then start your own business. you expect to save and deposit $7,500 a year for the first 6 years (t = 1 through t = 6) and $15,000 annually for the following 6 years (t = 7 through t = 12). the first deposit will be made a year from today. in addition, your grandfather just gave you a $32,500 graduation gift which you will deposit immediately (t = 0). if the account earns 9% compounded annually, how much will you have when you start your business 12 years from now?

Which of the following tasks would be a line cook's main responsibility? oa. frying french fries ob. chopping onions oc. taking inventory of stocked dry goods od. paying invoices