A welder drops a piece of red-hot steel on the floor. The initial temperature of the steel is 2,500 degrees Fahrenheit. The ambi
ent temperature is 80 degrees Fahrenheit. After 2 minutes the temperature of the steel is 1,500 degrees. The function f(t)=Ce(−kt)+80 represents the situation, where t is time in minutes, C is a constant, and k is a constant. After 2 minutes the temperature of the steel is 1,500 degrees. After how many minutes will the temperature of the steel be 100 degrees and therefore safe to pick up with bare hands?