Strontium-90 is a radioactive material that decays according to the function A(t) = Ao e -0.0244t, where A is the initial amount present and A is the amount present at time t (in years). Assume that a scientist has a sample of 400 grams of strontium-90. (a) What is the decay rate of strontium-90? (b) How much strontium-90 is left after 10 years? (c) When will only 100 grams of strontium-90 be left? (d) What is the half-life of strontium-90? (a) The decay rate of strontium-90 is 2.44 %. (Type an integer or a decimal. Include the negative sign for the decay rate.). (b) Approximately 313 grams of strontium-90 is left after 10 years. (Do not round until the final answer. Then round to the nearest whole number as needed.) (c) Only 100 grams of strontium-90 will be left in about years. (Do not round until the final answer. Then round to the nearest tenth as needed.).