1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Naddika [18.5K]
3 years ago
15

A toxic radioactive substance with a density of 9 milligrams per square centimeter is detected in the ventilating ducts of a nuc

lear processing building that was used 55 years ago. If the​ half- life of the substance is 20 ​years, what was the density of the substance when it was deposited 55 years​ ago?
Mathematics
2 answers:
Nutka1998 [239]3 years ago
5 0
<span>60.5 milligrams per square centimeter First, determine how many half lives have expired by dividing the time by the half-life. So: 55/20 = 2.75 That means that only 2^(-2.75) = 0.148650889 = 14.8650889% of the original substance remains. So just divide the amount remaining by 0.148650889 to get the original amount. 9 / 0.148650889 = 60.5445419 So originally, there was 60.5 milligrams per square centimeter 55 years ago.</span>
omeli [17]3 years ago
5 0

Answer:

<em>The density of the substance when it was deposited 55 years​ ago was </em><em>60.54 mg/cm³</em>

Step-by-step explanation:

The exponential function for growth and decay is,

y(t)=a(1\pm r)^t

where,

y(t) = the amount after time t

a = initial amount

r = rate of change

t = time period

+ is used for growth and - is used for decay.

As this is the case of decay, so the function becomes,

y(t)=a(1- r)^t

Given,

y(55) = 9 mg/cm³

r = 50% = 0.5  (as the substance is getting halved)

t = \dfrac{55}{20} = 2.75   (as the half life is 20 years and we have convert time in terms of half life)

Putting the values,

\Rightarrow 9=a(1- 0.5)^{2.75}

\Rightarrow 9=a(0.5)^{2.75}

\Rightarrow a=\dfrac{9}{(0.5)^{2.75}}

\Rightarrow a=60.54\ mg/cm^3

You might be interested in
Find the cube root of 2700
Liono4ka [1.6K]
It’s about 13.925. I rounded up
3 0
3 years ago
Read 2 more answers
What is the difference in length between the longest meteor and the shortest meteor ​
Bumek [7]

Answer:

Please show the full problem

Step-by-step explanation:

5 0
3 years ago
Read 2 more answers
Help ASAP<br><br> A)360<br><br> B)50<br><br> C)140
viktelen [127]
50

there’s no way x is 360 or 140
3 0
3 years ago
Read 2 more answers
PLEASE HELP CHOOSING BRAINLIEST
Rufina [12.5K]

Answer:

Hi friend here is your answer: C

Step-by-step explanation:

There friend hope it helps friend

Pls brainliest friend!!!!

8 0
2 years ago
PLEASE HELP ME WITH EMPIRICAL RULE!! ASAP!
Nat2105 [25]

Answer:

hahahahahahahahahahhahahahahhahahahahhahagagagaggagagagahhahahahahha

8 0
3 years ago
Other questions:
  • Draw the graph of each equation or inequality y= 4 / -3 +2
    15·1 answer
  • A map of a city shaped like a rectangle is given below on a grid. In 2012, there were 570 people per square kilometer) living in
    10·1 answer
  • Is 2340 divisible by 90
    13·1 answer
  • How many times can 8 go into 329
    13·2 answers
  • The free fall acceleration of an object under the influence of earths gravity 9.81. What is it’s value in I’m/min^2
    7·1 answer
  • Kami's front door is 3' wide and 7' tall. She purchased a circular table that is 8' in diameter. Will the table fit
    8·2 answers
  • Kiki recorded a video of her parakeet repeating phrases that she said. The video is 234 minutes long. Kiki watched the video 212
    8·1 answer
  • 3) Calculate the area of the entire triangle below. Show your work *<br><br> 22<br> 31<br> 8
    9·1 answer
  • he radioactive element​ carbon-14 has a​ half-life of 5750 years. A scientist determined that the bones from a mastodon had lost
    12·1 answer
  • What is 24.79 x 4,022 pls
    12·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!