The half-life of a certain radioactive material is 78 hours. an initial amount of the material has a mass of 790 kg. write an exponential function that models the decay of this material. find how much radioactive material remains after 18 hours. round your answer to the nearest thousandth.
a. y = 1/2 (1/790)^1/7 8x ; 0.107kg
b. y = 790 1/2 to 78x ; 0 kg
c. y = 22 (1/790) to the 1/78x ; 0.429 kg
d. y = 790 1/2 to the 1/78x ; 673.233 kg
i am not sure how to solve this problem, so an explanation would be incredibly !
you!