How to arrive at answer of 161

Consider a box model for a classroom of length l[m], width w[m], and height h[m]. The air change rate of the ventilation system is kV[hr1]. SARS-CoV-2 is emitted into the classroom in aerosol particles or droplets at a rate of E [viral RNA copies hr1 person 1 ] for a total number of infected people N. The particles are removed from the air by deposition with a rate constant of kd[hr1]. Assume in this problem that outside air contains zero viral RNA copies. Calculate the steady-state concentration of SARS-COV-2 in the classroom if there is an infected person talking in the room. On average, a talking person emits 10nL volume of aerosol per minute, with a viral load of 1000 viral RNA copies per nL. Assume kv=2.2hr1,kd=0.5hr1, N=1 infected person. The classroom dimensions are l=20m,w=11.5m, and h=6m. Round to the nearest whole number. (a) 1239 viral RNA copies per m3 (b) 2 viral RNA copies per m3 (c) 37 viral RNA copies per m3 (d) 27895 viral RNA copies per m3 (e) 161 viral RNA copies per m3