The half-life of a substance is found by using the equation A(t) = Age-kt where A(t) is the amount present at time t (years), k is the decay rate, and Ao is the initial amount of the substance present. Find the half-life of the substance. (Round your answer to the nearest year.) A radioactive substance whose decay rate is 0.6% per year Xyr 115

The formula for an exponential function is y= 54 x 0.94t , where t is measured in months.  Then the monthly percentage decay rate for y is  a.  0.94% b. 6.01% c. 0.06% d. 6%

Use the exponential decay equation A = A0 · 0.5t/8, where A is the amount of a radioactive material present after time t, and A0 is the original amount of the radioactive substance. Round to the nearest tenth.Iodine-131 is an isotope that is used to study the functioning of the thyroid gland. A patient is given an injection that contains 8 micrograms of iodine-131. (a) What is the iodine level in the patient after 14 days?A = _____micrograms(b) How long (in days) will it take for the iodine level to reach 5 micrograms?t = _____days