The half life of a certain radioactive material is 36 days. An initial amount of the material has a mass of 487 kg. Write an exponential function that models the decay of this material. Find how much radioactive material remains after 5 days. Round your answer to the nearest thousandth.
a)y=487(1/2)^36x ; 0.318kg
b)y=2(1/487)^1/36x ; 0.847kg
c)y=487(1/2)^1/36x ; 442.302kg
d)y=2(1/487)^36x ; 0kg
2 Answers

A = A(o)[0.5^(t/t(1/2)]
A = 487[0.5^5/36] = 487(0.9082) = 442.302kg
 .

c)
y = 487 * (1/2)^(x/36); 442.302
All the others have too little stuff left when only 5 days has past and you need 36 days to get to 1/2 of the stuff.