Iodine-131 is a radioactive isotope widely used in nuclear medicine to treat thyroid cancer. It has a half-life of 8 days.
A therapeutic dose of Iodine-131 was prepared at a manufacturing facility, but due to a logistics delay, the activity of the sample decreased from 1200 kBq1200\text{ kBq}1200 kBq to 75 kBq75\text{ kBq}75 kBq by the time it was delivered to the oncology clinic.
Determine the time, in days, that passed during this delivery delay.