Answer is 0.7 degrees celcius per minute
Explanation:
given that T(t) = 42-0.7t
We have to find the rate of drop of temperature.
For that we find drop of T in 1 minute
Consider T(t) for t minutes and t+1 minutes
T(t+1) = 42-0.7(t+1)
T(t) = 42-0.7t
Difference i.e. drop in temperature in one minute
= T(t+1)-T(t)
= 42-0.7(t+1)-(42-0.7t) =-0.7
Hence drop per minute = 0.7 degree celcius.
