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
UkoKoshka [18]
2 years ago
14

The half-life of a radioactive substance is 12 days. After 11 days a sample of the substance has been reduced to a mass of 7 mg.

Mathematics
2 answers:
Sloan [31]2 years ago
8 0
There is 8mg in all and that’s the answer
8_murik_8 [283]2 years ago
3 0

Answer:

  • 13.21 grams
  • 84.6 days

Step-by-step explanation:

The mass (m) remaining will be a function of the initial mass (m0) and the time in days (t) according to the exponential decay formula ...

  m = m0(1/2)^(t/12)

a) You want to find m0 for m=7 and t=11. Put these numbers in the formula and solve for m0.

  7 = m0(1/2)^(11/12) = 0.529732×m0

  m0 = 7/0.529732 = 13.21 . . . . grams

The initial mass of the sample was 13.21 grams.

__

b) We can use the value of m0 we found to determine the number of days until 0.1 mg will remain:

  0.1 = 13.21(1/2)^(t/12)

Dividing by 13.21 and taking logs, we have ...

  log(0.1/13.21) = (t/12)log(1/2)

  t = 12·log(0.1/13.21)/log(1/2) = 84.55

There will be only 0.1 mg left after 84.6 days.

_____

<em>Comment on the calculations</em>

For the latter part of the problem, be sure to use the full-precision value of  m0. Do not round any results until the final answer. Alternatively, you could use 7 mg for m0 and add 11 days to the result you get.

You might be interested in
In the diagram, what is the value of x?
Ghella [55]

Answer:

x = 162

Step-by-step explanation:

the sum of the interior angles of a quadrilateral = 360°

sum the interior angles of the quadrilateral and equate to 360

90 + 60 + x + 48 = 360 , that is

198 + x = 360 ( subtract 198 from both sides )

x = 162

5 0
2 years ago
Which description does not guarantee that a trapezoid is isosceles??
jasenka [17]

Answer:

Congruent bases does NOT guarantee that a trapezoid is isosceles.

8 0
3 years ago
PLZ TELL ME IF THIS IS RIGHT!!! THX
emmasim [6.3K]

Answer:

correct

Step-by-step explanation:

x means up and down and it is at -3

y means side to side and it is at -7

5 0
3 years ago
I need these answers ​
AVprozaik [17]

Answer:

You are correct with all of your answers so far,...

Step-by-step explanation:

5) = 0 (-17 + 20 = 3,... 3 + -3 = 0)

6) = -34 (-34 + 25 = -9,... -9 + -25 = -34)

9) = -4 (7 + -11 = -4)

Chow,...!

4 0
2 years ago
Read 2 more answers
How do I solve this math question? give full explanation using a formula. ​
lukranit [14]

Answer:

30 short cakes

Step-by-step explanation:

25ml = 10ml + 10ml +5ml

each 10ml of milk can make us 12 short cakes

we can two 10ml of milk (20ml) which can make us 24 short cakes.

but we have 25 ml of milk so how much does 5ml of milk give us if 10ml of milk gives us 12 short cakes ?

5ml makes us 6 short cakes. 24 short cakes plus 6 short cakes =30 shortcakes.

25ml of milk =10ml(12shortcakes)+ 10ml(12 shortcakes)+5ml(6 shortcakes)

6 0
3 years ago
Other questions:
  • F(x) = 3х+ 2<br> What is f(5)?<br> ОА. 15<br> Ов. 10<br> Ос. 21<br> OD. 17
    10·1 answer
  • How do you figure out the area of a triangle?
    5·2 answers
  • What is the surface area of a box that is 6 inches long, 2 inches wide, and 1 inch tall if it is scaled up by 10
    15·2 answers
  • Tried but still got it wrong,anyone??
    14·2 answers
  • Find parametric equations for the line parallel to r = (6,-8) and passing through P (9, -1)
    6·1 answer
  • Write an exponential function for a graph that passes through the points (2,16) and (3,32).
    14·1 answer
  • Given the function f (x)= x2+ x-4 with the domain d: {0,1,2,3} what is range R?
    5·1 answer
  • Does American accelerationism have human rights? # accelerationism
    5·1 answer
  • Can someone help me?
    11·1 answer
  • Inspired by the works of Neil Dawson and Bert Flugelman, Kassidy drafts a design for a modern sculpture celebrating education. T
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!