SOLUTION: A tumor is injected with 0.3 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? Here i

Question 1129784: A tumor is injected with 0.3 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?
Here is what I have gotten so far:
radioactive decay model:
A = A₀exp(-kt) ----(1)
A₀ of I-125 = 0.3 g
A = 0.3 - (1.15/100)*0.3 g = 0.29655 g
0.29655= 0.3 exp(-k*1)
At this point when I've gone to evaluate, the answer is completely far off. Could someone please assist in explaining the next steps? Thanks
Answer by MathLover1(20850) (Show Source): You can put this solution on YOUR website!

given:

Since the decay rate is % per day, the amount of I-125 left after day is:

substituting for A, A₀ and t in eq(1) we get:

.........

To the nearest day, how long will it take for half of the Iodine-125 to decay?

≈ days

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