How much water, at 100 degrees, was added to 4 kg at 10 degrees, and the temperature was set to 60 degrees?

To calculate the mass of added boiling water, we will use the equality: Sv * mk * (tk – tp) = Sv * mw * (tp – tb), whence we express: mk = mw * (tp – tb) / (tk – tp).

The values of the variables: mw is the mass of cold water (mw = 4 kg); tр – equilibrium temperature (tр = 60 ºС); tv – cold water temperature (tv = 10 ºС); tк – boiling water temperature (tк = 100 ºС).

Let’s make a calculation: mk = mw * (tr – tb) / (tc – tr) = 4 * (60 – 10) / (100 – 60) = 5 kg.

Answer: 5 kg of boiling water was added to 4 kg of cold water.