The 1 st Cumulant or moment (a 1) is used to calculate the intensity weighted Z average mean size and the 2 nd moment (a 2) is used to calculate a parameter defined as the polydispersity index (PdI). It is important to note here, that the Cumulants analysis algorithm does not yield a distribution â it gives only the intensity weighted Z average and the polydispersity index.
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Page 33 of 36 Edexcel International, I GCSE Mark Scheme with Examinersâ ReportMathematics 4400, June 2004 Question 7 One error was to leave the answer as 9/2, which scored 2 marks. An answer of 4.5 scoredno marks unless 9/2 or 4 1 / 2 was also seen.f a mark were lost, it was oftenthrough failure to draw an open circle at â2 on the number line. Page 30 of 36 Edexcel International, IGCSE Mark Scheme with Examinersâ ReportMathematics 4400, June 2004 Question 9 Many candidates scored full marks.