Abstract
1). For determination of grain size distribution, it is necessary to sift some volume of deposits. The sample size is discussed in this paper. The most useful is the treanlent as follow. At first, deposits aer stratified Into several strata and then cluster sampling method is used in every stratum.
2). And if we wish to know the ratio of rocks on minerals, sample size is also the important and. fundamental problem. Where p is the population ratio and n sample size, then the variance S2 is S2=pq/n in this case, q=1-p. Let the coefficient of variance of p be smaller than a, so we have the sample size n defind by n_??_pq l/a2•q/p. Fig. 1 shows n and p, in case a=0.10 and a=0.05.
