This is the boss. No calculator. Tonight a ton is $3.5\ \mathrm{kW}$, $\rho c$ for water is $4.2\ \mathrm{kJ}$ per litre per degree, and the evaporation coefficient stays at 0.0018 per °C of range — round numbers every plant engineer keeps for mental work and site sanity checks, and the values are chosen to fit in your head.

One chiller, one tower, one long problem, and every answer feeds the next: tonnage, then heat rejection, then the condenser water that carries it, then the evaporation that flow produces, then the verdict. Write each line down as you go — one early slip rolls all the way to the drain.

And note what the last line actually asks. It does not want another number; it wants a DECISION about the bleed, the way a service call really ends. The arithmetic is only there to earn you the right to make it. Remember the two rails: makeup always exceeds evaporation, and cycles are makeup over BLOWDOWN — never over evaporation, because evaporation carries no minerals out at all.

Everything in the chapter rides in this one plant room. 5★ under par here is the chapter crown. Clock in.