3. solve (-7) + b = (-11)

The radioactive isotope radium has a half-life of 1,600 years. The mass of a 100-gram sample of radium will be______ grams after

Olenka [21]

To solve this we are going to use the half life equation $N(t)=N_{0} e^{( \frac{-0.693t}{t _{1/2} }) }$
Where:
$N_{0}$ is the initial sample
$t$ is the time in years
$t_{1/2}$ is the half life of the substance
$N(t)$ is the remainder quantity after $t$ years

From the problem we know that:
$N_{0} =100$
$t=200$
$t_{1/2} =1600$

Lets replace those values in our equation to find $N(t)$ :
$N(200) =100e^{( \frac{(-0.693)(200)}{1600}) }$
$N(200)=100e^{( \frac{-138.6}{1600} )}$
$N(200)=100e^{-0.086625}$
$N(200)=91.7$

We can conclude that after 1600 years of radioactive decay, the mass of the 100-gram sample will be 91.7 grams.

8 0

3 years ago

The area of polygon MNOPQR = Area of a rectangle that is 9 square units + Area of a rectangle that is ___ square units. (Input w

vekshin1

You have the polygon MNOPQR which can be expressed as two rectangles pasted one next to each other.

To see the two rectangles in the picture, you can draw a line parallel to segment MR througn point N.

From the original picture you can state the dimensions of both rectangles.

Call S, the point where the line that you drew intercepts the segment RQ.

Then one rectangle is MNSR and the other rectangle is OPQS.

The measures of the sides of the rectangle MNSR are:

- the length of MN = length of SR = base

- the length of MR = the length of NS.= height

So its area is base * height, which you can all A1.

The measured of the rectangle OPQS are:

- segment OP = segment SQ = segment QR - segment SR = base

- segment PQ = segment OS = height

So its area is base * height, which you can call A2.

Then the area of the polygon MNOPQRS is A1 + A2. One of them is 9 u^2 and the other is what the answer is asking for, and that you have calculated above.

With this procedure you can tell the value needed.

8 0

3 years ago

Solve, using the correct order of operations, when x = 7 and y = 3 (x – 3) + 2y

sweet [91]

Answer:

10

Step-by-step explanation:

Since it given that:

x = 7 and y = 3

We can substitute x and y:

(7-3) + 2(3)

7 - 3 = 4

4 + 2(3)

2(3) = 6

4 + 6 =10

Thus the answer is 10.

[RevyBreeze]

8 0

2 years ago

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In a group of 25 students, 16 are female. What percentage of the group is female?

asambeis [7]

Percent is out of 100, and 25*4=100. So multiply 16*4=64, so the answer is 64%

3 0

3 years ago

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If an equation is an identity, then how many solutions does it have? zero one infinite

dezoksy [38]

Answer:

Infinite solutions.

Step-by-step explanation:

If an equation is an identity, then there will be infinite solutions that the identity will have.

Let, us assume that an identity equation is given by

(a + b)² = a² +2ab + b².......... (1)

Now, putting any real values of a and b the identity will be satisfied.

Therefore, there are infinite solutions for an identity equation. (Answer)

3 0

3 years ago

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