Particle Technology

Particle size and distributions

Problems 2.9

Question 1
The following size distribution was obtained for glass spheres by microscope examination. Complete the table rows:

Size range (um): <5 5-7 7-10 10-15 15-20 20-30 30-40 40-50 >50
Number in range: 0 50 150 200 55 45 20 5 0
Relative number: 0 0.0952 0.2857 0.3810 0.1048 0.0857 0.0381 0.0095 0
Cumulative number undersize: 0 0.0952 0.3810 0.7619 0.8667 0.9524 0.9905 1 1
Relative number per micron range: 0 0.0476 0.0952 0.0762 0.0210 0.0086 0.0038 0.0010 0

See the different types of graphs that these distributions give by clicking on the row labels. Note that the relative number per micron range is a fairer comparison of the frequency of occurrence of particles as the DX is now equal (per micron range), compared to the original data which had variable DX values. For example, 2 microns for the grade 5 to 7, 10 microns for the grade 40 to 50 microns. Also, what is the area under the curve; i.e. what does it integtrate to?

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