Math please help!
posted by Alexia on .
Nuclear medicine technologists use the Iodine isotope I131, with a halflife of 8 days,to check thyroid function of patients. After ingesting a tablet containing the iodine, the isotopes collect in a patient's thyroid, and a special camera is used to view its function. Suppose a person ingests a tablet contaiing 9 microcuries of I131. To the nearest hour, how long will it be until there are only 2.8 microcuries in the person's thyroid?

2.8=9*e^(6.93 t/(8*24))
ln (2.8/9)=6.93 t/182
solve for t in hours. I get about 31 hours 
the answers are given, it is 324 hours. im just not sure how to get that.

where did you get 6.93 and 24 from?

m(t)=9x2^(t/192) 192=24x8
2.8=9x2^(t/192)
t=192xln(9/2.8)/ln2
t=323.4236495