Calculate Mm from the equation Mm= In(2)/(px)> with X1/2 determined from the graph. Counts-Bkg (min-1) vs Pb Thickness (cm) Counts-Bkg (min-1) -0.266*x + 2.82 2.8 2.7 2.6 Counts-Bkg (min-1) 2.5 2.4 2.3 0.0 0.5 1.0 1.5 Pb Thickness (cm)Pb thickness log(Counts-bkg) O 2.822 0.1588 2.803 0.2381 2.768 0.3175 2.760 0.3969 2.710 0.4763 2.695 0.5556 2.676 0.635 2.605 0.7144 2.623 0.7938 2.530 1.27 2.452 1.6933 2.425