Homework: 6.8 Homework Window Help View History Bookmarks Fri 9:52 PM Abdullah A
ID: 3037892 • Letter: H
Question
Homework: 6.8 Homework Window Help View History Bookmarks Fri 9:52 PM Abdullah Almalaabi Math 126B Spring 2017 HW Score: 096, 0 of 5 p Score: 0 of 1 pt 2 of 510 complete) Question Help 6.8.3 Strontium 90 is a radioactive material that decays according to the function Aco Ao e ".where An is the intal amourt present and Ais the amount present at time in years) Assume that a scientist haa a sample of 500 grams of strontium 90. (a) What is the decay rate of strontium 90? (b) How much strontum 90 is left after 10 years? (c) When wil only 200 grams of strontium 90 be d What is the har ire of strontium 90? (a) What is the decay rate of strontium 90? L% Type an integer or a decimal. Include the negative sign for the decay rate Enter your answer in the answer box and then click Check AnswerExplanation / Answer
A(t) = Aoe^-0.0244t
Ao = 500 gms
a) Decay rate = - 0.0244 = - 2.44%
b) After 10 yrs ; find A(10)
A(10) = 500e^(-0.0244*10) = 391.744 gms
c) when will A(t) = 200 gms
200 = 500e^(-0.0244*t)
e^(-0.0244t) = 0.4
take ln on both sides: t = ln(0.4)/0.0244 = 37.553 days
d)Half life = 0.693/decay constant = 0.693/0.0244 = 28.278 days
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.