the bill from your electrician was $198. he worked for 3 hours. the cost for materials was $33. how much did the electrician charge you per hour

About 92 days are taken for 90 % of the material to decay.

The mass of radioisotopes ([tex]m[/tex]), measured in milligrams, decreases exponentially in time ([tex]t[/tex]), measured in days. The model that represents such decrease is described below:

[tex]m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }[/tex] (1)

Where:

In addition, the time constant is defined in terms of half-life ([tex]t_{1/2}[/tex]), in days:

[tex]\tau = \frac{t_{1/2}}{\ln 2}[/tex] (2)

If we know that [tex]m_{o} = 85\,mg[/tex], [tex]t_{1/2} = 27.7\,d[/tex] and [tex]m(t) = 8.5\,mg[/tex], then the time required for decaying is:

[tex]\tau = \frac{t_{1/2}}{\ln 2}[/tex]

[tex]\tau = \frac{27.7\,d}{\ln 2}[/tex]

[tex]\tau \approx 39.963\,d[/tex]

[tex]t = -\tau \cdot \ln \frac{m(t)}{m_{o}}[/tex]

[tex]t = -(39.963\,d)\cdot \ln \frac{8.5\,mg}{85\,mg}[/tex]

[tex]t\approx 92.018\,d[/tex]

About 92 days are taken for 90 % of the material to decay.

We kindly invite to check this question on half-life: https://brainly.com/question/24710827

Answer:

Step-by-step explanation:

We have to think that the median and the side is parallel to are one small and one big, and that the small one is half of that big one and that the big one is the small one doubled.

AB = 8 ( the small one ) then XY = 2* 8 = 16 ( the big one)

AB = 3 then  XY = 2* 3 = 6

AB = 2.5 then XY = 2*2.4 = 5

XY = 18 ( the big one)  then AB = 18/2 = 9 ( the small one)

XY = 4 then AB = 2/2 = 2

XY = 9 then AB = 9/2 = 4.5

Answer:

4 times

Step-by-step explanation:

there is 16 cups of water in a gallon

16/4=4

Answer:i)16y^2−4x^2

ii) i don't know the other one sorry

Step-by-step explanation:

Answer:

Step-by-step explanation:

6.15/5=1.23

The answer is B.

Answer:

Step-by-step explanation:

Sum of all the angles of the polygon = (n -2) *180  

                                                             = (6 - 2) * 180 = 4 *180 = 720

45 + 135 + 45 + 135 + x + 3x = 720

          360 + 4x = 720

                     4x = 720 - 360

                    4x = 360

                       x = 360/4

x = 90

3x = 3*90 = 270

Answer:

x= -64, y= 55

Step-by-step explanation:

x=-y-9

6(y-9)-5y=1

6y-54-5y=1

y=55

x=-55-9

x=-64

Answer:

{x=-4

{x= -5

Step-by-step explanation:

Substitute into one of the equations:6(- y -9) - 5y=1

Apply Multiplicative Distribution Law:- 6y-54-5y=1

Rearrange unknown terms to the left side of the equation:-6y -5y = 1+54

Combine like terms:- 11y= 1+54

Calculate the sum or difference:-11y=55

Divide both sides of the equation by the coefficient of variable:y= 55÷(-11)

Remove the parentheses:y = -55÷11

Calculate the product or quotient:y=-5

Substitute into one of the equations:x=-(-5)-9

Remove the parentheses:x=5-9

Calculate the sum or difference:x=-4

The solution of the system is:{x=-4

{x=-5.

Answer:

ok good morning

have a nice day

Step-by-step explanation:

#toxicsquad

Answer:

i think its 7, but you should probably check that...

Option c since the equation shifts 2 units vertically up compared to parent square root function

The velocity of the car is the rate of change of distance over time.

The car comes to a complete stop at 12 seconds

The velocity function is given as:

[tex]\mathbf{V(t) = 0.5t^2 - 8t + 24}[/tex]

When the car comes to a complete stop, V(t) = 0.

So, we have:

[tex]\mathbf{0.5t^2 - 8t + 24 = 0}[/tex]

Expand

[tex]\mathbf{0.5t^2 - 6t - 2t + 24 = 0}[/tex]

Factorize

[tex]\mathbf{0.5t(t - 12) - 2(t - 12) = 0}[/tex]

Factor out t - 12

[tex]\mathbf{(0.5t - 2)(t - 12) = 0}[/tex]

Split

[tex]\mathbf{(0.5t - 2) =0\ or\ (t - 12) = 0}[/tex]

Solve for t

[tex]\mathbf{0.5t =2\ or\ t = 12}[/tex]

This gives

[tex]\mathbf{t =4\ or\ t = 12}[/tex]

12 > 4.

Hence, the car comes to a complete stop at 12 seconds

Read more about velocity and time at:

https://brainly.com/question/19979064

Answer:

Well if you add up all 3 angles in a triangle you’d get 180 degrees as the answer.

So we can. Jus substitute.

For number 19 you can do this

57+x+x+87+50=180

Now combine like terms

194+2x=180

Now solve

x=-7

Now we can subsitute that into angle A

57+ (-7) which is 50

Measure of angle A is 50.

For number 19 it’s the same thing.

9x+14+16x-4+80=180

Now combine like terms

25x+90=180

Solve

25x= 90

x= 3.6

Now subsitue for A

3.6*9+4 which is 36.4

A is 36.4

Answer:

y = 1/6x - 9

Step-by-step explanation:

The slope-form intercept formula is y = mx + b

Answer:

5+5=10

Step-by-step explanation:

i dont understand

Answer:

See below for answer.

Step-by-step explanation:

∠ECB ≅ ∠FBC    Parallel lines cut by a transversal form congruent alternate  

                             interior angle  

Δ AEC ≅ Δ DFB   ASA                

V = s^3 = 8^3 = 512cm^3 True.

Answer:

every answer:

A

B

B

B

B D E

A

C

C

C

D

Step-by-step explanation:

i got 100% on Edg

Answer:

1st , 2nd , and 4th

Step-by-step explanation:

Answer:

What grade are you my brother is good at this stuff

Answer:

The last one (16+20+3+8)

Step-by-step explanation:

add up all the sides not including the 3 inside

Answer:

(16+20+3+8)

Step-by-step explanation:

The perimeter is the measurement on the outside of the shape.

so (3+16+20+8) = 47

Answer:

50 is sum of gcf its couldn't of 19 is 20

Answer:

Step-by-step explanation:

This is a permutation of 7 letters with double O and double C:

P = 1

I = 1

C = 2

O = 2

L = 1

--------

p = N! ÷ k!

p = 7! ÷ 2!2!

p = 5,040 ÷ 4

P = 1,260

Answer:

[tex] \mathsf{ \frac{m + 21}{5} = n }[/tex]

Step-by-step explanation:

To make "n" the subject of the formula, rearrange the formula so it begins with " n = "

To isolate the variable "n", you need to inverse the other terms on that side of the equation where "n" really is.

=> m = 5n - 21

=> m + 21 = 5n - 21 + 21

=> m+ 21 = 5n

[tex] \mathsf{ \frac{m + 21}{5} = n }[/tex]

Answer:

VW = 4 cm

Step-by-step explanation:

Congruent chords are equidistant from the centre , so

VW = UV = 4 cm

Answer:

If one of the data points has the form \displaystyle \left(0,a\right)(0,a), then a is the initial value. Using a, substitute the second point into the equation \displaystyle f\left(x\right)=a{\left(b\right)}^{x}f(x)=a(b)

​x

​​ , and solve for b.

If neither of the data points have the form \displaystyle \left(0,a\right)(0,a), substitute both points into two equations with the form \displaystyle f\left(x\right)=a{\left(b\right)}^{x}f(x)=a(b)

​x

​​ . Solve the resulting system of two equations in two unknowns to find a and b.

Using the a and b found in the steps above, write the exponential function in the form \displaystyle f\left(x\right)=a{\left(b\right)}^{x}f(x)=a(b)

​x

​​ .

Step-by-step explanation:

Answer: 6

Step-by-step explanation:

Let's look at two points on this line (1, 5), and (0, -1)

Using the slope formula ([tex]\frac{y_2-y_1}{x_2-x_1}[/tex])

[tex]\frac{((5) - (-1))}{(1)-(0)}[/tex]

[tex]\frac{6}{1}[/tex]

Hope it helps :)

Answer:

Well you could count and use the Rise/Run method, or you could use the Slope formula (x2 - x1) / (y2 - y1)

From point (0, -1) to point (1, 6) would look like this

(1 - 0) / (6 + 1) = 1/7, so your slope is 1/7

Since you already have you y-intercept (where x is 0), your whole equation would be this:

y = 1/7x - 1

Answer:

His average monthly payment is $730.83

Step-by-step explanation:

700+650+750+760+785+880+700+725+700+750+720+650=8,770

8,770/12 = 730.83