Question Statement:
A ground feed sample undergoes sieve analysis using a standard set of 7 sieves (Tyler mesh sizes 3/8-inch, 4, 8, 14, 28, 48, and 100). The cumulative percentages of material retained on these 7 sieves are found to be $0\%$, $12\%$, $28\%$, $48\%$, $68\%$, $84\%$, and $96\%$. The fineness modulus ($FM$) of the ground sample is ________ (round off to 2 decimal places).