Question

Strontium 90 is a radioactive material that decays according to the function A()-A 00244t, where Ao is the initial amount time t (n years). Assume that a scientist has a sample of 500 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 400 grams of strontium 90 be left? (d) What is the half-life of strontium 902 (a) What is the decay rate of strontium 907 E2.44% (Type an integer or a decimal Include the negative sign for the decay rate.) (b) How much strontium 90 is left after 10 years? Approximately grams (Do not round undi the final answer. Then round to the nearest whole number as needed.) (c) When will only 400 grams of strontium 90 be left? In about years. (Do not round untilthe final answer. Then round to the nearest tenth as needed) (d) What is the half-ife of strontium 907 yyears. Than nind to the nearest tenth as needed.)

Answer 1

(a) Decay rate = -2.41% (according to my calculation in R programming software and Excel)

(b) A(10) = 500 * exp(-0.0244 * 10) = 392 grams.

(c) t = (log_e(400/500))/(-0.0244) = 9.1 years

(d) Half life = log_e(2)/0.0244 = 28.4 years