A student is trying to determine the half-life of the radioactive isotope Idoine-131. She’s measuring the amount of iodine in a sample every 8 hours.

The data obtained is shown on this table:
Time (in hours) Iodine-131 (in grams)
0 =4.80
8 =4.66
16 =4.51
24 =4.39
32 =4.29
40 =4.14
48 4.04