This question is from Elementary Survey Sampling by Richard L. Scheaffer:

I need the full answer for this question and the correct one please .

A county government is interested in expanding the facilities of a daycare center for mentally retarded children. The expansion will increase the cost of enrolling a child in the center. A sample survey will be conducted to estimate the proportion of families with retarded children that will make use of the expanded facilities. The families are divided into those who use the existing facilities and those who do not. Some families live in the city in which who use the existing facilities and those who do not. Some families live in the city in which the center is located, and some live in the surrounding suburban and rural areas. Thus, stratied random sample is used, with users in the city , users in the surrounding country, nonusers in the city, and nonusers in the country forming strata 1,2,3, and 4, respectively. Approximately 9% of the present users and 5% of the present nonusers will use the expanded facilities. The cost of obtaining an observation from a user is $4 and from a nonuser is $3. The difference in cost results because nonusers are difth to locate. Existing records give N1 = gift; 2 43., N3 = 145, and N4 = '53. 1} Suppose that the total cost of sampling is xed at Mill]. Choose the sample size and allocation that minimizes the variance of the estimator 13,, for this xed cost