c) Assuming that at the time of release, 800 workers were exposed to the escaping ammonia for 1200 s, using the probit relationship given by Eq. (5) and Figure QC-1, determine the ammonia concentration that would result in 160 of the workers dying. Pr = -15.6 +1.0 ln(C2.6t) (5) Where: Pr is the probit value 6 C is the concentration of ammonia, ppm t is exposure duration, s [8 marks] 100 90 80 70 60 Lethality Percentage 50 40 30 20 10 0 0 4 5 9 Probit Value Figure Qc-1: Lethality vs Probit value for ammonia