Page 2
Enter the probability to decay in a time unit – approximately 0.083 for Iodine 131 to decay in one day. Also make a row of day numbers 0 to 30.
Page 3
Enter 1000 1’s (shown in Col B below) and Sum them at the top of the column under the Day numbers.
Page 4
Use IF and RAND() to simulate decay (a change from 1 to 0).
Page 5
Copy the formula down. (Get the “thin cross” and double click.)
Page 6
Copy the sum formula over. You should see about 8.3% of the “atoms” decayed.
Page 7
Copy the formula for the simulated atoms and the sum over for the 30 days.
Page 8
Highlight the Day and Sum rows and make an XY Scatter graph.
Page 9
Fit to an Exponential, label axes, title, etc.
Page 10
Interpolation
• According to your fit formula, what percentage of atoms are left (un-decayed) after 8 days?
• 16 days? • 24 days?