There was a sample of 700 milligrams of a radioactive substance to start a study. Since then, the sample has decayed by 3.1% each year. Let t be the number of years since the start of the study. Let y be the mass of the sample in milligrams.Write an exponential function showing the relationship betweenand y and t.

Answer:y = 700 (0.969)^t Step-by-step explanation:Using the depreciation formula after a given period of time.A = P (1- r/100)^nWhere, A is the initial value P is the original valuer is the rate of depreciation and n is the time taken in years Therefore;A will be the new mass of the sample after decay,yP is the original mass of the sample before decay, 700 mgr is the rate of decay each year, 3.1% and n is the number of years, tHence;y = 700 (1- 3.1/100)^ty = 700 (96.9/100)^ty = 100(0.969)^t