1. Find the critical value z/2 that corresponds to the confidence level 95%.
2. A clinical trial tests a method designed to increase the probability of conceiving a girl. In the study 330 babies wereborn, and 297 of them were girls. Use the sample data to construct a 99% confidence interval estimate of the percentage of girls born. Based on theresult, does the method appear to beeffective?

____ < p< _____

(Round to three decimal places asneeded.)

Does the method appear to beeffective?

No, the proportion of girls is not isnot significantly different from 0.5.

Yes, the proportion of girls is significantly different from 0.5.

3 . You are the operations manager for an airline and you are considering a higher fare level for passengers in aisle seats. How many randomly selected air passengers must yousurvey? Assume that you want to be 95% confident that the sample percentage is within 3.5 percentage points of the true population percentage. Complete parts(a) and(b) below.

a. Assume that nothing is known about the percentage of passengers who prefer aisle seats.

n= ____

nothing

(Round up to the nearestinteger.)

b. Assume that a prior survey suggests that about 39% of air passengers prefer an aisle seat.

n=____

nothing

(Round up to the nearestinteger.)