# Question f4db5

Dec 21, 2017

T= 33,3°C

#### Explanation:

in first approxitation you can make a proportion:
$\frac{{T}_{1} - {T}_{2}}{{T}_{1} - {T}_{f}} = \frac{{T}_{2} - {T}_{3}}{{T}_{2} - {T}_{f}}$
that is
(50°C-40°C)/(50°C-20°C)= (40°C- T_3)/ (40°C-20°C)
10/30=(40°C- T_3)/ (20°C)
20°C/3= (40°C- T_3)#
T3 = 33,3°C
but it is possible only because ithe time considered in the two cases are the same: 5 minutes. Otherwise you must calculate the constant of time.