The half-life of a certain radioactive material is 68 hours. An initial amount of the material has a mass of 641 kg. Write an exponential function that models the decay of this material. Find how much radioactive material remains after 4 hours. Round your answer to the nearest thousandth.

A) y = 641(1/2)^68x; 0 kg
B) y = 1/2(1/641)^1/68x; 0.342 kg
C) y = 641(1/2)^1/68x; 615.390 kg
D) y = 2(1/641)^1/68x; 1.367 kg
Please help if you know. Will give medals!!!

Question

The half-life of a certain radioactive material is 68 hours. An initial amount of the material has a mass of 641 kg. Write an exponential function that models the decay of this material. Find how much radioactive material remains after 4 hours. Round your answer to the nearest thousandth.

A) y = 641(1/2)^68x; 0 kg
B) y = 1/2(1/641)^1/68x; 0.342 kg
C) y = 641(1/2)^1/68x; 615.390 kg
D) y = 2(1/641)^1/68x; 1.367 kg
Please help if you know. Will give medals!!!

anonymous · Answer

A left = A original (1/2)^time/half life
y = 641(1/2)^4/68
y=641 (1/2)^1/17
y=647(.960)
y=621.150
this is what i got?

anonymous · Answer

So which answer of the answer choices do you think it would be?