Where:
P90 = 90th percentile confidence level mercury concentration, in pounds per million Btu.
mean = Arithmetic average of the fuel mercury concentration in the fuel samples analyzed according to § 63.11213 , in units of pounds per million Btu.
SD = Standard deviation of the mercury concentration in the fuel samples analyzed according to § 63.11213 , in units of pounds per million Btu.
t = t distribution critical value for 90th percentile (0.1) probability for the appropriate degrees of freedom (number of samples minus one) as obtained from a Distribution Critical Value Table.
40 C.F.R. §63.11211