The mass of a growing cyst at clock time t is given by m = .04 * t³, where m is mass in grams and t is clock time in months.

• At what average rate is the mass changing between clock times t = 13.2 and t = 13.3 months? 
• At what average rate is the mass changing between clock times t = 13.2 and t = 13.21 months? 
• At what average rate is the mass changing between clock times t = 13.2 and t = 13.201 months? 
• What do you estimate is the rate at which mass is changing at clock time t = 13.2 months?

The rate at which the mass of the cyst changes is given by Rate = .019 * t², where Rate is rate of change in grams per month and t is clock time in months.  How much do you think mass will change between t = 13.2 and t = 26.4 months?