REASONING A radioactive substance has a half-life of 32 years. a. Determine the value of k to the nearest hundred-thousandth and use this value to determine the equation of decay for this radioactive substance. Use y for the amount of substance after time : and use a for the initial value. y = ae 0.02166r Correct Answer y = de .021661 Part B Incorrect X 2 tries left. Please try again. b. How much of a 5-gram sample of the radioactive substance should be left after 100 years? Round to the nearest hundredth. about