Answer:
21.68 minutes ≈ 21.7 minutes
Step-by-step explanation:
Given:
Initial temperature
T = 100°C
Final temperature = 60°C
Temperature after (t = 3 minutes) = 90°C
Now,
using the given equation
at T = 90°C and t = 3 minutes
or
taking the natural log both sides, we get
3k =
or
3k = -0.2876
or
k = -0.09589
Therefore,
substituting k in 1 for time at temperature, T = 65°C
or
or
or
taking the natural log both the sides, we get
( -0.09589)t = ln(0.125)
or
( -0.09589)t = -2.0794
or
t = 21.68 minutes ≈ 21.7 minutes