The average grain diameter for a brass material was measured as a function of time at 650°C, which is shown in the following table at two different times:

Time (min)______________ Grain Diameter (mm)

40 ......................................... 5.6 × 10-2

100 ....................................... 8.0 × 10-2

(a) What was the original grain diameter?

(b) What grain diameter would you predict after 200 min at 650°C?