Welcome :: Homework Help and Answers :: Mathskey.com

Recent Visits

    
Welcome to Mathskey.com Question & Answers Community. Ask any math/science homework question and receive answers from other members of the community.

13,435 questions

17,804 answers

1,438 comments

774,951 users

What is the decay rate of strontium 90?

0 votes

Strontium 90 is a radioactive material that  decays  according  to  the  function A (t) = A0 e^- 0.0244t, where A0 is the initial amount present and A is the amount present  at  time  t (in  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 400 grams of strontium 90 be left?
(d) What is the half-life of strontium 90?
                  

asked Jan 24, 2015 in PRECALCULUS by anonymous

1 Answer

0 votes

Step 1 :

(a)

 The amount image of a radioactive material present at time image is image.

Where image is the original amount of the radioactive material and image is a negative number that presents a rate of decay.

Find the decay rate of strontium 90 :

 

The function is image.

Compare the function with image.

image

The decay rate of strontium 90 is image

Step 2 :

(b)

The function is image.

Substitute image and image in the function.

image

After 10 years, 391.74 grams of strontium 90 be left.

Step 3 :

(c)

The function is image.

Substitute image and image in the function.

image

After 9.15 years, 400 grams of strontium 90 be left.

answered Jan 24, 2015 by lilly Expert
edited Jan 24, 2015 by bradely

Step 4 :

(d)

The function image.

Half-life of the function image.

Substitute image in the function.

The function is .

Solve for image.

image

Half-life of strontium 90 is 28.4 years.

Solution :

(a) The decay rate of strontium 90 is image

(b) After 10 years, 391.74 grams of strontium 90 be left.

(c) After 9.15 years, 400 grams of strontium 90 be left.

(d) Half-life of strontium 90 is 28.4 years.

Related questions

...