1. A cup of tea is placed on a table. At a time of t minutes after being placed on the table, its temperature in degrees Celsius is given by T=

20+Aekt Where A and k are positive constants. The initial temperature of the tea was 70°C. a) Find the value of A b) The tea takes 4 minutes to decrease in temperature from 70°C to 50°C. Show that k = In (3)