Physical sample size

Hi Guys:

     I got a question.Hope someone can help me. Thanks.

   There is a example in the library for calculating the physical sample size.

          Sample size = 150 + 200 + 100 = 450.

I did test it with the same quantity, but my sample size is 200,the system only take the max quantity from there 3 operations as the sample.Could someone tell me why?