Refer to the data in Exercise 17.2. Determine the sample size for Copenhagen under each of the following schemes.
a. Proportional allocation
b. Optimum allocation for the overall population mean.

Data From Exercise 17.2

A researcher in Denmark is studying the reading habits of the people in the country. His sample that comprises three different cities—Aarhus, Esbjerg, and Copenhagen. Assume there are 150 households in Aarhus, 40 in Esbjerg, and 85 in Copenhagen. The researcher randomly selected 20 households from Aarhus, 10 from Esbjerg, and 15 from Copenhagen and recorded the weekly average reading times (in hours) for each households. From the record, he found that the weekly average reading time for Aarhus is 35.73 hours, Esbjerg is 26.24 hours, and Copenhagen is 18.31 hours. The sample standard deviations for Aarhus, Esbjerg, and Copenhagen were 1.56 hours, 4.78 hours, and 2.49 hours, respectively.