PLEASE HELP PLEASE I NEED TO KNOWW

Answer:

The half-life of this radioactive substance is of 8.6 months.

Step-by-step explanation:

Exponential decay of an amount:

The equation that models an amount after t units of time, subject to exponential decay, is given by:

[tex]A(t) = A(0)(1-r)^t[/tex]

In which A(0) is the initial amount and r is the decay rate, as a decimal.

A radioactive substance decays to 30% of its original mass in 15 months.

This means that [tex]A(15) = 0.3A(0)[/tex]. We use this to find 1 - r.

[tex]A(t) = A(0)(1-r)^t[/tex]

[tex]0.3A(0) = A(0)(1-r)^{15}[/tex]

[tex](1-r)^{15} = 0.3[/tex]

[tex]\sqrt[15]{(1-r)^{15}} = \sqrt[15]{0.3}[/tex]

[tex]1 - r = (0.3)^{\frac{1}{15}}[/tex]

[tex]1 - r = 0.9229[/tex]

So

[tex]A(t) = A(0)(0.9229)^t[/tex]

Determine the half-life of this radioactive substance to the nearest tenth.

This is t for which A(t) = 0.5A(0). So

[tex]A(t) = A(0)(0.9229)^t[/tex]

[tex]0.5A(0) = A(0)(0.9229)^t[/tex]

[tex](0.9229)^t = 0.5[/tex]

[tex]\log{(0.9229)^t} = \log{0.5}[/tex]

[tex]t\log{0.9229} = \log{0.5}[/tex]

[tex]t = \frac{\log{0.5}}{\log{0.9229}}[/tex]

[tex]t = 8.6[/tex]

The half-life of this radioactive substance is of 8.6 months.

what is the question?? because this equation is false?

Answer:

x = 33

y = 5

Step-by-step explanation:

Answer:

16P5

Step-by-step explanation:

16*15*14*13*12

Answer:

((y + 2) ^ 2)/25 - ((x - 3) ^ 2)/4 = 1 O A. ( (3, - 2 plus/minus sqrt(21)) B. (3, - 2 plus/minus sqrt(29)) O B. O c. D . (3 plus/minus sqrt(21), - 2); (3 plus/minus sqrt(29), - 2)

The foci of the hyperbola will be (3, -2 + √29) and (3, -2 - √29). Then the correct option is B.

The hyperbola is the locus of a point such that the difference of distance from point P to two non-movable points. These two points are called foci of hyperbola.

The hyperbolic equation is given as,

(y - k)² /a² - (x - h)² /b² = 1

Then the foci of the hyperbola are given as,

(h, k + c) and (h, k - c)

The equation of the hyperbola is given below.

(y + 2)² /25 - (x - 3)² / 4 = 1

Compare the equations, then we have

(h, k) = (3, -2)

a² = 25

b² = 4

Then the value of 'c' is given as,

c² = a² + b²

c² = 25 + 4

c² = 29

c = √29

Then the foci of the hyperbola will be (3, -2 + √29) and (3, -2 - √29). Then the correct option is B.

More about the hyperbola link is given below.

https://brainly.com/question/12919612

#SPJ2

Answer:

Chi-Square and Linearization ... A random sample of 315 subjects is selected and represented in the table below. ... claim that aerobic walking and cholesterol levels are related.

92, 110, 128, 146, 164, 182. ✅

[tex]\large\mathfrak{{\pmb{\underline{\red{Step-by-step\:explanation}}{\orange{:}}}}}[/tex]

[tex]92,110,128,146,164,182 \\ ➵ \: 92 + 18 = 110 \\ ➵ \: 110 + 18 = 128 \\ ➵ \: 128 + 18 = 146 \\ ➵146 + 18 = 164 \\ ➵ \: 164 + 18 = 182[/tex]

[tex]\large\mathfrak{{\pmb{\underline{\orange{Happy\:learning }}{\orange{.}}}}}[/tex]

Answer:

The radian :

[tex] \frac{2\pi}{3} [/tex]

Answer:

y = 5 sin (2x) + 4

Step-by-step explanation:

this is sines function,

the amplitude is [9 - (-1)]/2 = 10/2 = 5

the period is 2πx/π = 2x

the x-axis of actual function is at y = 4

so, the function is :

y = 5 sin (2x) + 4

Answer:

The area of the canvas must be 30 feet.

Step-by-step explanation:

Answer: I thin it’s Opposite of 2

Step-by-step explanation:

Answer:

The distance between A and D

Step-by-step explanation:

when it is |-2| (in the box) it changes to 2

Answer:

1/5

Step-by-step explanation:

y = 12

12 = 1/5 x 60

12= 12

y = 9

9 = 1/5 x 45

9 = 9

and so on and it always results to one fifth

Answer:

B

Step-by-step explanation:

the dimensions of the rectangle when its area is 9cm^2

Answer:

26 units

Step-by-step explanation:

make a proportion: so sides correspond alongside eachother.

so, 15/10 =24/Y, i know you need to solve for x, but you have to find the other blank length.

now cross multiply, 10*24=15*Y

240=15Y

240/15=

Y= 16

now add Y to the length 10 to get X. So you get 10+16=26

Answer:

The sentence

"The Number of Chem textbooks sold is 86 less than the number of History textbooks"

This seems to be the confusing part.

Now look at it this way...

'If CHM text is 86 less than History text... It also means that History Text is 86 More than CHM'

This expression can be written as

Let History Text be "H"

Let CHM text be "C"

C - 86 = H

or

C=H + 86.......1

First line of this question is interpreted thus

H + C = 326.......2

From eqn 1... C=H+86

Substitute into Eqn 2

H + C=326

H + (H+86)=326

H+H=326-86

2H=240

H=240/2

H=120.

C=H+86

C=120+86

C=206.

This answer is correct... Why?

The key statement says .. The Number of CHM sold is 86 less than History...

Also interpreted as

The Number of CHM – 86 = History

206 - 86 =120.

Have a great day!!!

Answer:

y = 5/4x - 14

Step-by-step explanation:

Given:

Passes through (8, -4)

Slope (m) = 5/4

Slope-intercept equation:

y - y1 = m(x - x1)

y - (-4) = 5/4(x - 8)

y + 4 = 5/4x - 10

y = 5/4x - 14

Answer:

96 m

Step-by-step explanation:

It is given that the two overlapping triangles are similar in the figure.

The landowner wishes to find the distance across the pond. The distance is d.

From the figure, since the two triangles are similar, therefore we can write :

[tex]$\frac{d}{(24+40)}=\frac{60}{40}$[/tex]

[tex]$\frac{d}{64}=\frac{60}{40}$[/tex]

[tex]$d = \frac{60}{40} \times 64$[/tex]

[tex]$d = \frac{6}{4} \times 64$[/tex]

d = 6 x 16

  = 96 m

Therefore, the distance across the pond is d = 96 m

Answer:

C

Step-by-step explanation:

the bank loans the borrower

hope it help

Answer:

6,10,14,18,22

Step-by-step explanation:

4n+2

Let n=1  4(1)+2 = 4+2 = 6

Let n=2  4(2)+2 = 8+2 = 10

Let n=3  4(3)+2 = 12+2 = 14

Let n=4  4(4)+2 = 16+2 = 18

Let n=5  4(5)+2 = 20+2 = 22

Answer:

235.619 is my answer since I have done V = (pi) radius squared and height/3

Step-by-step explanation:

Answer:

2x+3

f(-2)=:2x+3

2(-2)+3

-4+3

= -1

Answer:

y=3x

Step-by-step explanation:

Answer:

Approximately 169

Step-by-step explanation:

Set up as fractions and use cross multiplilcation to solve for the unknown.

These are our fractions from the information we are given; the winners represent the numerators (and x is the unknown, becuase we don't yet know how many winners there will be with 50000 participants). Note that the denominator on the first fraction is (1476 + 5) because we want it to represent TOTAL amount of particpants in the ratio:

[tex]\frac{5}{1481} = \frac{x}{50000}[/tex]

Now cross multiply by multiplying numerators and denominators that are ACROSS from each other, so 5 * 50000 and 1481 * x; now we have:

250000 = 1481x

Now to isolate x (to know its value) we need to divide both sides by 1481, and we are left with:

168.8 = x

But I rounded up to 169.

Answer:

5

Step-by-step explanation:

-75 divided (-15) = 5

Answer:

32.5%

Step-by-step explanation:

Answer:

32.5

Step-by-step explanation:

divided by 100 to get percentage

Area = π × ( radius )^2

Area = π × ( 18 )^2

Area = π × 324

Area = 324 π mm^2

Answer:

[tex]p' = 0.22[/tex]

Step-by-step explanation:

Given

[tex]p = \frac{78}{100}[/tex]

Required

Probability that a [tex]customer[/tex] does [tex]not[/tex] live [tex]within[/tex] [tex]50[/tex] miles

To do this, we make use of complement rule;

Which states that:

[tex]p + p' = 1[/tex]

Make p' the subject

[tex]p' = 1 - p[/tex]

So, we have:

[tex]p' = 1 - \frac{78}{100}[/tex]

Express fraction as decimal

[tex]p' = 1 - 0.78[/tex]

[tex]p' = 0.22[/tex]

Answer:

The first term is 8

The common ratio is 2, because the ratio of 8:16 is 1:2 and the ratio of 16:32 is 1:2

Step-by-step explanation:

Answer:

The common ratio of the following geometric sequence is x2 everytime.