A certain population is divided into five strata so that N1 = 2000, N2 = 2000, N3 = 1800, N4 = 1700, and N5 = 2500. Respective standard deviations are: s1 = 1.6, s2 = 2.0, s3 =4.4, s4 = 4.8, s5 = 6.0 and further the expected sampling cost in the first two strata is BDT 4 per interview and in the remaining three strata the sampling cost per interview are BDT 5 , BDT 6 and BDT 7, respectively. How should a sample of size n = 226 be allocated to five strata considering situations? 6 (i) Calculate proportionate sampling where assume that there are no difference in sampling cost and no stratum variability. (ii) Consider disproportionate sampling where only the differences in within-stratum variability exist but no differences in stratum sampling costs. (iii) Consider disproportionate sampling where both the within-stratum variability and the differences in stratum sampling costs exist.