I know how to go about solving this problem, setting it up as A=Ce^kt and whatno

Question

I know how to go about solving this problem, setting it up as A=Ce^kt and whatnot, it is just crucial that arrive at the exact answer it is asking for due to it being submitted online with no work shown.

Any help would be greatly appreciated! Will rate best answer with clear directions of how the answer was solved.

Three years ago, there were 7 grams of a radioactive substance. Now there are 3 grams. How much will there be 2 years from now? Do not round until the very end. Round your final answer to 2 decimal places. Do not enter in the units. That is. do not enter the word "grams."

Explanation / Answer

A = C e^(-kt)

A(0) = 7 = C

A = 7 e^(-kt)

A(3) = 3 = 7*e^(-3k)

e^-3k = 3/7

-3k = ln(3/7) = -0.8472978603872037

k = -0.8472978603872037/-3 = 0.2824326201290679

A(5) = 7* e^(-5k) = 7*e^(-5*0.2824326201290679) = 1.70531023195559656

from now after 2 years it will be 1.70

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