Answer:
k = 0.0916
Step-by-step explanation:
T(t) = [tex]T_{s} + ( T_{o} - T_{s} )e^{-kt}[/tex]
from question; t = 12 mins , [tex]T_{s}[/tex] = 50 C , [tex]T_{o}[/tex] = 80 C , T = 60 C
60 = 50 + (80 - 50) [tex]e^{-12k}[/tex]
60-50 = 30 [tex]e^{-12k}[/tex]
10/30 = [tex]e^{-12k}[/tex] (Taking natural Log of both sides)
In(0.3333) = In [tex]e^{-12k}[/tex]
-1.0986 = -12k
k = 0.0916