steady state concetration

*To*: mathgroup at smc.vnet.net*Subject*: [mg129621] steady state concetration*From*: jeremy <j.witoslawska at gmail.com>*Date*: Wed, 30 Jan 2013 22:05:12 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net

Hi, i'm new in Mathematica and i've a project to do. i've to find at what time 90% of the steady state concetration of C is achieved. and soo far i have something like that, for 3 different k values: With[{k = 0.3}, eqn1s = 0 == k (1/2 - z[t]) (1/3 - z[t])]; With[{k = 0.6}, eqn2s = 0 == k (1/2 - z[t]) (1/3 - z[t])]; With[{k = 0.9}, eqn3s = 0 == k (1/2 - z[t]) (1/3 - z[t])]; Evalute[{eqn1s, eqn2s, eqn3s}] NSolve[Evaluate[{eqn1s, eqn2s, eqn3s}], z[t]] and what i get in NSolve is supposedly be the steady state, but i don't know how to find this 90% and my profesor told me that i could try do this with DSolve, but something doesn't work. i hope that someone will be able to help me with this. Thanks

**Follow-Ups**:**Re: steady state concetration***From:*"Louis Talman" <talmanl@gmail.com>