A radioactive substance decays exponentially: The mass at time t is m(t) = m(0)e^kt, where m(0) is the initial mass and k is a negative constant. The mean life M of an atom in the substance is
[infinity]
M = âk â« te^kt dt.
0

For the radioactive carbon isotope, 14C, used in radiocarbon dating, the value of k is -0.000121. Find the mean life of a 14C atom.

Answers

Answer 1

Answer:

mean life = 8264.5 s

Step-by-step explanation:

k = - 0.000121

The relation is given by

[tex]m = mo e^{kt}[/tex]

Now, the mean life is the life time for which the sample retains.

The mean life is the reciprocal of the decay constant.  

The relation between the mean life and the decay constant is

[tex]\tau =\frac{1}{k}\\\\\tau = \frac{1}{0.000121} = 8264.5 seconds[/tex]


Related Questions

Which side of the pentagon on the right corresponds to
side KJ on the pentagon on the left.

Answers

Answer:

side st.

Step-by-step explanation:

st corresponds to kj since a it has five sides.

what are the answers to the questions below?

Answers

Answer:

You have to follow PEMDAS or parenthesis, exponents, multiplication, division, addition, and subtraction. It's an order to solve equations. I listed the steps and the answers for you below :) I have throughly checked them so they should be correct! yw :D

Step-by-step explanation:

1. 5x + 4x - 6x = 24

9x - 6x = 24

3x = 24

24/3 = 8

x = 8

2. 8y + 5 - 4y + 1 = 46

8y - 4y = 4y

5 + 1 = 6

4y + 6 = 46

4y = 46 - 6

4y = 40

40/4 = 10

y = 10

3. 33 = 5 ( x + 8 ) + 3

33 =  5x + 40 + 3 (because we distributed)

33 = 5x + 43

5x + 43 = 33 (just rewriting it to make it easier)

5x = 33 - 43

5x = -10

-10/5 = -2

so x = - 2

4. 2m + 3 ( m - 8 ) = 1

2m + 3m - 24 = 1

we got 3m - 24 because we distributed the 3

5m - 24 = 1

5m = 25

25/5 = 5

m = 5

5. p + p - 2p + 4p = - 48

2p - 2p + 4p = - 48

4p = - 48

- 48 / 4 = - 12

p = - 12

6. 2 ( y + 5 ) + 3y = 25

2y + 10 + 3y = 25

5y + 10 = 25

5y = 25 - 10

5y = 15

15/5 = 3

y = 3

7. 1/4 h + 3/4 h + 1/2 h + 2 = 5

1/4 h + 3/4 h + 1/2 = 3/2 h

3/2 h + 2 = 5

3/2 h = 5 - 2

3/2 h = 3

h = 2

8. 60 = 4 ( k + 3 ) + 2 ( k - 3 )

60 = 4k + 12 + 2k - 6

4k + 12 + 2k - 6 = 60

6k + 6 = 60

6k = 60 - 6

6k = 54

k = 9

9. - 2 ( d + 1.4 ) - 1.8 = 20.6

-2d + - 2.8 - 1.8 = 20.6

-2d - 2.8 = 22.4

-2d = 25.2

d = - 12.6

10. 8 - 2 ( w + 4 ) = 10

8 + - 2 w + - 8 = 10

-2w + 9 + - 8 = 10

-2w = 10

10 / -2 = -5

w = -5

Find the product of 2x cubed and x squared minus 5x minus 4. Problem number 23

Answers

Answer:

2x^5-10x^4-8x^3

Step-by-step explanation:

2x^3 ( x^2 - 5x-4)

Distribute

2x^3 * x^2  - 2x^3 -5x  -2x^3 *4

2 x^(3+2) - 10 x^(3+1) - 8x^3

2x^5-10x^4-8x^3

y = 95°, find the measure of x

Answers

9514 1404 393

Answer:

  x = 100°

  y = 95°

Step-by-step explanation:

It is probably easier to find y first. Opposite angles of an inscribed quadrilateral are supplementary, so ...

  y = 180° -85° = 95°

The measure of an arc is double the measure of the inscribed angle subtending it. The arc subtended by angle y is ...

  90° +x = 2y

  x = 190° -90° = 100°

_____

Additional comment

The rule cited above regarding opposite angles of an inscribed quadrilateral comes from the theorem regarding inscribed angles. In the given diagram, the diagonal from the bottom vertex to the top one is a chord that divides the circle into two arcs. Their sum is 360°. The inscribed angle theorem tells you ...

  2y +2(85°) = 360°

  y + 85° = 180° . . . . . . . divide by 2; opposite angles are supplementary

Consider this polynomial, where a is an unknown real number.

correctly/incorrectly
and why

Answers

9514 1404 393

Answer:

incorrectly; used 1 in the division instead of -1incorrectly; evaluated higher powers of -1 incorrectly

Step-by-step explanation:

The result each should have obtained is ...

  a +10 = 17

  a = 7

Braulio's mistake was in using 1 as his divisor instead of -1. His bottom row should have been 1, 4, a-4, 1-a, a +10.

Zahra's mistake was improperly evaluating higher powers of -1. Her evaluation should have been 1 -5 +a +3 +11 = a +10.

A four digit password is a number that begins with a 3. If digits can be repeated how many possible passwords are there? show and explain your work

Answers

Answer:

The answer is 1,000

SInce the beginning number is 3 and there are ten possible numbers to put in the remaining three slots, there are exactly 1,000 possible combinations for a 3-digit code. The answer is 1,000. There are 3 rows of 10 digits. The number of combinations 10 to the thid power which is 1000 (10 * 10 * 10)

A polynomial function has real coefficients, a leading coefficient of 1, and the zeros -6, 1, and 1. Write a polynomial function of least degree in standard form.​

Answers

Answer:

[tex]{ \sf{ \underline{ {x}^{2} + 5x - 6 }}}[/tex]

Step-by-step explanation:

[tex](x + 6)(x - 1) \\ = {x}^{2} - x + 6x - 6 \\ = {x}^{2} + 5x - 6[/tex]

How much more area does a large pizza with a 12 in. diameter have than a small pizza with an 8 in. diameter? Round your answer to the nearest square inch.

Answers

Answer: About 63 in²

Step-by-step explanation:

Area of circle = π · r²

r = radius lengthπ ≈ 3.14

Area of large pizza:

[tex]\pi *r^{2} =3.14*6^{2} =3.14*36=113.04[/tex]

Area of small pizza:

[tex]\pi *r^{2} =3.14*4^{2} =3.14*16=50.24[/tex]

Difference in area:

[tex]113.04-50.24=62.8[/tex]

For the function G defined by G(x) = 5x + 3, find G(2)

Answers

G(x)=5x+3

[tex]\\ \sf\longmapsto G(2)[/tex]

[tex]\\ \sf\longmapsto 5(2)+3[/tex]

[tex]\\ \sf\longmapsto 10+3[/tex]

[tex]\\ \sf\longmapsto 13[/tex]

Option c is correct

13, replace x as 2 and then solve, 5(2)+3 which is 10+3 which equals 13.

6) Frazer cycles the first 20 miles at an average speed of 21mph. The second
part is more uphill, and he only manages 13mph. By what percentage did his
speed decrease?
How to solve

Answers

9514 1404 393

Answer:

  38.1% decrease

Step-by-step explanation:

A percentage change is found from ...

  % change = (change)/(original amount) × 100%

  = (new value - original amount)/(original amount) × 100%

  = (13 -21)/21 × 100% = -8/21 × 100% ≈ -38.1%

Frazer's speed decreased by 38.1% during the second part.

_____

Additional comment

A negative % change represents a decrease; a positive % change represents an increase.

A postal worker can sort a day's worth of mail in 8 hours. With her
supervisor helping, it takes 3 hours. How long would it take the
supervisor working alone?

Answers

Answer:

6 hours.

Step-by-step explanation:

x = supervisor's hours alone

Since there are two people working together, you need to incorporate some kind of 2 in this problem.

If the postal worker was cloned, it would take 4 hours.

3 x 2 = 6.

Issac put $5 in a shoe box every day for the months of april, may, and june. He then spent 75% of the money on baseball cards. How much money is left in his shoe box.

Answers

As of 2021:
April-$150
May-$155
June-$150
Total-$455
Spent 75%=455/100x75
=341.25
455-341.25=$113.75
Round off to 3sf: $114
Have a good day

Please
Help me asap!!

Answers

Answer:

z -2 = 10

Step-by-step explanation:

11z-9-10z+7 = 10

Combine like terms on the left side

11z -10z     -9+7  =10

z -2 = 10

Answer: z=12

Step-by-step explanation:

[tex]11z-9-10z+7=10\\z-9+7=10\\z-2=10\\z=12[/tex]

what is differnciation​

Answers

Answer:

Differentiation is concerned with things like speeds and accelerations, slopes and curves ect. These are Rates of Change, they are things that are defined locally. The Fundamental Theorem of Calculus is that Integration and Differentiation are the inverse of each other.

Operations and scientific notation math project need to know how to find the scientific notation

Answers

Answer:

how did not orderstan that

How many ways are there to rearrange the letters of the word: COMBINATION?

Answers

Answer: 4,989,600 different ways

Step-by-step explanation:

Hello! Please help thanks

Answers

Answer:

A. [tex]\frac{5}{13}[/tex]

Step-by-step explanation:

Hi there!

We are given right triangle PQR, with PR=5, RQ=12, and PQ=13

We want to find the value of sin(Q)

Let's first recall that sine is [tex]\frac{opposite}{hypotenuse}[/tex]

In reference to angle Q, PR is the opposite side, RQ is the adjacent side, and PQ is the hypotenuse

So that means that sin(Q) would be [tex]\frac{PR}{PQ}[/tex]

Substituting the values of PR and PQ gives sin(Q) as [tex]\frac{5}{13}[/tex], which is A

Hope this helps!

akram is 20 year old and his sister shazia is 15
1-what was the ratio of their ages before 4 years
2-what was the ratio of their ages after 5 years
3-what do the above two points explain about ratios

Answers

Answer:

1) akram : shazia

20-4 : 15-4

16 : 11

2) akram : shazia

20 + 5 : 15 + 5

25 : 20

5 : 4

3) ratios are not always constant

A.Yes, since the slopes are the same and the y-intercepts are the same.
B.No, since the y-intercepts are different.
C.Yes, since the slopes are the same and the y-intercepts are different.
D.No, since the slopes are different.

Answers

Answer:

C

Step-by-step explanation:

one line is

y = 3x/7 + 11

its slope is 3/7

the y-intercept is, of course, when x=0. there y=11

the other is

-3x + 7y = 13

7y = 3x + 13

y = 3x/7 + 13/7

its slope is 3/7 (the same as the other line)

the y-intercept (x=0) is y = 13/7 (different to the other line)

Answer:

C. Yes, since the slopes are the same and the y-intercepts are different.

Step-by-step explanation:

[tex]y=\frac{3}{7} x+11[/tex]  and [tex]-3x+7y=13[/tex]

→ Rearrange the second equation to make y the subject

7y = 3x + 13

→ Divide everything by 7

[tex]y=\frac{3}{7} x+\frac{13}{7}[/tex]

A sample of 4 children was drawn from a population of rural Indian children aged 12 to 60 months. The sample mean of mid-upper arm circumference was 150 mm with a standard deviation of 6.73. What is a 95% confidence interval for the mean of mid-upper arm circumference based on your sample

Answers

Answer:

The 95% confidence interval for the mean of mid-upper arm circumference based on your sample is between 139.29 mm and 160.71 mm.

Step-by-step explanation:

We have the standard deviation for the sample, which means that the t-distribution is used to solve this question.

The first step to solve this problem is finding how many degrees of freedom,which is the sample size subtracted by 1. So

df = 4 - 1 = 3

90% confidence interval

Now, we have to find a value of T, which is found looking at the t table, with 3 degrees of freedom(y-axis) and a confidence level of [tex]1 - \frac{1 - 0.95}{2} = 0.975[/tex]. So we have T = 3.1824

The margin of error is:

[tex]M = T\frac{s}{\sqrt{n}} = 3.1824\frac{6.73}{\sqrt{4}} = 10.71[/tex]

In which s is the standard deviation of the sample and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 150 - 10.71 = 139.29 mm

The upper end of the interval is the sample mean added to M. So it is 150 + 10.71 = 160.71 mm

The 95% confidence interval for the mean of mid-upper arm circumference based on your sample is between 139.29 mm and 160.71 mm.

Write each percent as a fraction in simple form 15 3/5%

Answers

Answer:

39/250

Step-by-step explanation:

15 3/5 = 78/5 and percent means per 100, so

(78/5)/100 = (78/5)(1/100)

=78/500 = 39/250

please give me correct answer​

Answers

Answer:

150 e udi,auwdbkhg

disha

eiwiwisj8293

ajesjhf

8ઈઘુઘ

Please help i need the answer asap!!!
if you know the answer please give it to me as soon as you can!!

Answers

Answer:

35 cm

Step-by-step explanation:

You can use the Cosine Rule to find the length of a side when two sides and the included angle are given.

a² = b² + c² - 2bc cos A

a² = (36²) + (52²) - 2(36)(52) cos 42°

a² = (1296) + (2704) - (3744)(0.7431448255)

a² = (4000) - (2782)

a² = 1218

a = ✓1218

a = 34.9 cm

A train traveling at 30 miles per hour reaches a tunnel which is 9 times as long as the train. If the train takes 2 minutes to completely clear the tunnel, how long is the train? (1 mile = 5,280ft)

Answers

I honestly don’t know because I honestly don’t know

y you work from 7 a.m. to 4 p.m. The state you live in requires that you take a 30-minute break during any shift longer than 6 hours. This break does not count towards your hours. How many hours did you work today? Remember 30 minutes is equal .5 hours​

Answers

Answer:

You’ve worked 7 hours and 30 minutes

Step-by-step explanation:

12 workers take 4 hours to complete a job. How long would it take 15 workers to complete the job?

Answers

Answer:

3.2 hours

Step-by-step explanation:

12 workers * 4 hours = 48 worker hours

15 workers  * x hours = 48 worker hours

48 /15 =3.2 hours

Answer:

3 hours and 12 minutes.

Step-by-step explanation:

12 Workers complete a job in 4 hours

1 worker complete a job 12 × 4 = 48

15 workers complete a job = 48/15 = 3³/¹⁵ = 3¹/⁵

= 3 hours + 1/5 × 60  minutes = 3 hours 12 minutes.

find x on this special right triangle, 45 is not an option!!!!

Answers

let the line between 2 tria be y

sin 60/8√2 = sin 90/y

y=13.06

sin 45/13.06 = sin 90/x

x=18.46

Answer:

First, find the hypotenuse of the right triangle with the 60° & 30°.

Hypotenuse = hsin(x) = opposite side/hypotenuse

[tex]sin(60) = \frac{8\sqrt{2}}{h} \\\\sin(60)h=8\sqrt{2}\\\\\frac{\sqrt{3}}{2} h=8\sqrt{2}\\\\h=\frac{8\sqrt{2}}{\frac{\sqrt{3}}{2}}=8\sqrt{2}*\frac{2}{\sqrt{3}} =\frac{16\sqrt{2} }{\sqrt{3}} =\frac{16\sqrt{2}(\sqrt{3}) }{\sqrt{3}(\sqrt{3})} =\frac{16\sqrt{6} }{3}[/tex]

Use that side length to find x.

sin(x) = opposite side/hypotenuse

[tex]sin(45)=\frac{\frac{16\sqrt{6}}{3}}{x}\\\\sin(45)x=\frac{16\sqrt{6}}{3} \\\\\frac{\sqrt{2}}{2}x=\frac{16\sqrt{6}}{3} \\\\x=\frac{\frac{16\sqrt{6}}{3}}{\frac{\sqrt{2}}{2}}=\frac{16\sqrt{6}}{3}*\frac{2}{\sqrt{2}}=\frac{16\sqrt{2}\sqrt{3}(2)}{3\sqrt{2} }=\frac{32\sqrt{3} }{3}[/tex]

What is the derivative of (x + 1) sin x?

Answers

Answer:

By the Sum Rule, the derivative of 1−sin(x) 1 - sin ( x ) with respect to x x is ddx[1]+ddx[−sin(x)] d d x [ 1 ] + d d x [ - sin ( x ) ] .

Quadrilaterals STUV and ABCD are congruent. The side length of each square on the grid is 1 unit.

A. only sequence a
B. only sequence b
C. both
D. neither
_______________________________
use the image below !

Answers

Answer:

both

Step-by-step explanation:

Congruent shapes have equal corresponding side lengths

The true statement is (c) both

To map the quadrilaterals on one another, then the sequence of transformation must be rigid transformation

The given sequence of transformations are both rigid, and they both would map quadrilaterals STUV and ABCD

Hence, the true statement is (c) both

Read more about transformation at:

https://brainly.com/question/4289712

20 POINTS! The answer is x=4 and x= -5, how should I word it, saying how he is wrong?

Answers

Answer:

The student took the numbers for the factors 5, -4 for the zeros  instead of solving the equation

The zeros are -5, 4

Step-by-step explanation:

x^2 +x - 20=0

What 2 number multiply to -20 and add to 1

5*-4 = -20

5+-4 = 1

(x+5)(x-4) =0

Using the zero product property

x+5 = 0  x-4 =0

x=-5  x=4

Answer:

Solution given:

equation is:

x²+x-20=0

doing middle term factorisation

note:we need to get 1 while subtracting factor of the product of constant and coefficient of x².

20*1=20=2*5*2*1

we get 1 while subtracting 5-2*2=5-4

now substitute value 5-4 at coefficient of x

we get

x²+(5-4)x-20=0

now

distribute

x²+5x-4x-20=0

taking common from each two term

x(x+5)-4(x+5)=0

again taking common (x+5) and keeping remaining at another bracket

(x+5)(x-4)=0

either

x+5=0

x=-5

or

x-4=0

x=4

Error is:

x= 4 not -4

x=-5 not 5.

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