A tumor is injected with 0.8 grams of iodine-125, which has a decay rate of 1.15% per day. to the nearest day, how long will it take for half of the iodine-125 to decay?

If the initial amount is 0.8 grams, half of this amount would be 0.4 grams. But first, let's construct an equation for the decay rate. That would be:

Amount left = Initial amount * (1 - Decay Rate) * Time

0.4 = 0.8 (1 - 0.0115) (t)

Solving for t,

t = 0.51 days

Technically, it's just half day. But if we convert to the nearest day, the answer would be 1 day.