Use the fact that the quantity of a radioactive substance after t years is given by
q = q0(2−t/k),
where q0 is the original amount of radioactive material and k is its half-life (the number of years it takes for half the radioactive substance to decay).

The half-life of strontium-90 is 25 years. Find the amount of strontium-90 remaining after 20 years if
q0 = 87 kg.
(Round your answer to the nearest kg.)

Answers

Answer 1

Answer:

  50 kg

Step-by-step explanation:

Put the given numbers into the given formula and do the arithmetic.

  q = q0(2^(-t/k))

  q = (87 kg)(2^(-20/25)) = (87 kg)(0.574349)

  q ≈ 50 kg

The amount remaining after 20 years is about 50 kg.


Related Questions

2.5 times 1,760 in steps.

Answers

Answer:

2.5 times 1760 is 4400

Step-by-step explanation:

math lol

Answer:

. We assume, that the number 1760 is 100% - because it's the output value of the task.

2. We assume, that x is the value we are looking for.

3. If 1760 is 100%, so we can write it down as 1760=100%.

4. We know, that x is 2.5% of the output value, so we can write it down as x=2.5%.

5. Now we have two simple equations:

1) 1760=100%

2) x=2.5%

where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that:

1760/x=100%/2.5%

6. Now we just have to solve the simple

equation, and we will get the solution we are looking for.

7. Solution for what is 2.5% of 1760

1760/x=100/2.5

(1760/x)*x=(100/2.5)*x - we multiply both sides of the equation by x

1760=40*x - we divide both sides of the equation by (40) to get x

1760/40=x

44=x

x=44

Use the four-step definition of the derivative to find f'(x) if f(x)= -3x^3 + 10.

Answers

We can use the power rule to solve this,

-3x^3+10

-9x^2

The power rule is multiple the power then subtract it since 10^1 1-0 is 0 it does not give us anything. Hope this is helpful!

Please like and brainliest comment for concerns

After all tryouts are completed, the school will be hosting a party for all the new athletes. At the party, hot dogs and hamburgers will be provided to all athletes and their guests, if they choose to bring a guest. The ratio of hot dogs purchased to number of guests is 1:0.8. Determine how many hot dogs you would need if 150 people attend the party. Explain how you found your answer.

Answers

120 hotdogs would be served if 150 people attend the party.

Ratio

A ratio is the quantitative relationship between two value, showing how many times one number contains another.

The ratio of hot dogs purchased to number of guests is 1:0.8. For 150 people:

Number of hotdogs = 150 * 0.8/1 = 120 hotdogs

Therefore 120 hotdogs would be served if 150 people attend the party.

Find out more on Ratio at: https://brainly.com/question/2328454

PLEASE HELP ASAP!!!!( 50 POINTS)

Chef Alfredo invested $4800 at a simple interest rate of 5% and can now afford a $6,000 state-of-the-art pizza
oven. How many years ago did he make this investment? Show all your work and answer in a complete sentence.

Answers

5 % of 4800 is 240
next you would do 6000 divided by 240 which gives you 25
so the answer would be 25 years

15 is nine more than j

Answers

Answer:

here ya go.

Step-by-step explanation:

15=j+9

subtract 9 from both sides.

j= 6

Can you help with this problem?

Find the area.

Answers

Answer:

132 sq cm

Step-by-step explanation:

There is a rectangle on top of your shape and a trapezoid below.

Area of a rectangle:

A = length•width

A = 7•4

A = 28sq cm

Area of a trapezoid:

A= 1/2(b_1 + b_2)•h

A=1/2(19 + 7)•8

=1/2(26)•8

=13•8

=104 sq cm

Area of total:

A_rect + A_trapzd

=28 + 104

= 132 sq cm

3. Choose the single logarithmic expression that is equivalent to the one shown.
log; 4 - log2
log 2
O
log 4
O
log, 2
log, 3

Answers

Answer:

log, 2

Step-by-step explanation:

the answer is log, 2 or c

The solution of the single logarithmic expression that is equivalent to the one shown is,

⇒ log₃ 2

What is an expression?

Mathematical expression is defined as the collection of the numbers variables and functions by using operations like addition, subtraction, multiplication, and division.

We have to given that;

The expression is,

⇒ log₃4 - log₃2

Now, We can simplify as;

⇒ log₃4 - log₃2

⇒ log₃4/2

⇒ log₃ 2

Thus, The solution of the single logarithmic expression that is equivalent to the one shown is,

⇒ log₃ 2

Learn more about the mathematical expression visit:

brainly.com/question/1859113

#SPJ5

On Monday, Janelle earned $21 for 7 hours of babysitting. Getting paid the
same rate, she earned $48 for babysitting on Saturday. How many hours
did Janelle babysit on Saturday? *

Answers

Answer:

16

$21 ÷ 7 = 3

which means she get $3 each hour she babysit

$48 ÷ 3 =16

Step-by-step explanation:

hope it helps

pls mark me as brainliest I need it

The volume of the figure is 9ft 15ft 15ft 15ft please help fast PLEASE!

Answers

Step-by-step explanation:

Formulas.

Square: [tex]V = L \times W \times H[/tex]

Square Pyramid: [tex]V = \frac13b^2h[/tex]

b = base.

Let's work on the square first.

Substitute the Length, Width, and Height of the square into the formula:

[tex]V=15 \times15\times15[/tex]

Solve:

[tex]V=15^{3} =3,375[/tex]

Let's work on the square pyramid.

Substitute 225 into the formula, and 9 (height):

[tex]V=\frac{1}{3}(15)^2(9)[/tex]

Solve:

[tex]V=\frac{1}{3}225(9)[/tex]

[tex]V=\frac{1}{3}(2025)[/tex]

[tex]V=675[/tex]

Add each volume:

[tex]3,375+675=4,050 ft^{3}[/tex]

The total volume of the figure is [tex]4,050 ft^{3}[/tex].

this one too please help me learn math

Answers

Answer:

[tex]x=\frac{1}{2}[/tex]

Step-by-step explanation:

equation of a circle:  [tex](x - h)^2+(y-k)^2=r^2[/tex]

where (h, k) = center and r = radius

From inspection, we can see that the center of the circle = (0, 0)

and the radius = 1

[tex]\implies (x - 0)^2+(y-0)^2=1^2[/tex]

[tex]\implies x^2+y^2=1[/tex]

Substitute [tex]y=\frac{\sqrt{3}}{2}[/tex]  into  [tex]x^2+y^2=1[/tex]  and solve for [tex]x[/tex]:

[tex]\implies x^2+(\frac{\sqrt{3}}{2})^2=1[/tex]

[tex]\implies x^2+\frac{3}{4}=1[/tex]

[tex]\implies x^2=\frac{1}{4}[/tex]

[tex]\implies x=\pm \sqrt{\frac{1}{4}}[/tex]

[tex]\implies x=\pm\frac{1}{2}[/tex]

As point P is in quadrant 1, [tex]x[/tex] is negative, so [tex]x=\frac{1}{2}[/tex]

help I WILL GIVE Brainiest!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
What is the solution to the system of equations?

-1/2x+1/2y=-1

x-y=2

a. There is no solution.

b. There are infinitely many solutions.

c. There is only one solution, (3, 1).

d. There is only one solution, (–6, –8).

Answers

Answer:

b. infinite solutions

Step-by-step explanation:

[tex]-\frac{1}{2}x+\frac{1}{2}y=-1\\\\\textsf{subtract} \ -\frac{1}{2}y \ \textsf{from both sides:}\\\\\implies -\frac{1}{2}x=-1-\frac{1}{2}y\\\\\textsf{mulitply both sides by -2:}\\\\\implies x=2+y\\\\\textsf{subtract} \ y \ \textsf{from both sides:} \ x-y=2[/tex]

Therefore, the graphs are the same.

If the graphs of the equations are the same, then there are an infinite number of solutions that are true for both equations.

Answer:

There's one solution (2,0)

Hope this helps!

Lin uses an app to graph the charge on her phone.


When did she start using her phone?

When did she start charging her phone?

While she was using her phone, at what rate was Lin’s phone battery dying?

Answers

Answer:

See below

Step-by-step explanation:

Use the graph to answer the following questions:

When did she start using her phone?

At 2 afternoon

When did she start charging her phone?

At 8 afternoon

While she was using her phone, at what rate was Lin’s phone battery dying?

From 100% to 40% between 2PM and 4 PM:

(100 - 40)/(4 - 2) = 60/2 = 30% per hour

Answer:

she start using her phone at 2 hours after noonshe start charging her phone at 8 hours after noon.rate when Lin’s phone battery dying: [tex]\frac{40-100}{4-2}[/tex] : [tex]\frac{-60}{2}[/tex] : [tex]-30[/tex]%/hr

{ observation from the graph given }

9. Which is the quadratic equation the
best fits the scatterplot?
A. f(x) = x² – 8x + 22
B. f(x)=-X2 – 8x-10
C. f(x)=-x? + 8x - 32
D. f(x)=-x? + 8x-10

Answers

Answer:

c

Step-by-step explanation:

can you please solve this question please​

Answers

Answer:

false

Step-by-step explanation:

x=1

4+24= 24

28=24

flase

A coordinate plane with a line graphed passing through (negative 2.5, negative 5) and (2.5, 0).
Which input was substituted into the function f(x) = x to create the given graph?

f(x + 2.5)
f(x – 2.5)
f f (StartFraction 5 Over 2 EndFraction x)
f f (StartFraction 2 Over 5 EndFraction x)

Answers

Answer:

um i dont understand sorry

Answer:

B

Step-by-step explanation

How many is x - 87 = 13 just answer pls

Answers

Answer:

100

Step-by-step explanation:

I hope this helps you

x - 87= 13
x-87+87=13+87
the answer is x=100

2. If final price of an article is Rs.2000 and the discount is 50% then the marked price of the article is ______.
(a) Rs.2050 (b) Rs.4200 (c) Rs.4000 (d) Rs.2400

Answers

The marked price of the article is (c)Rs.4000

Layla is baking a Double Chocolate Chocolate Chip cake. For this recipe, she will need one bag of flour and a number of bags of chocolate chips. At the grocery store, she sees that a bag of flour costs $3.59 and each bag of chocolate chips, c, costs $2.75. Write an algebraic expression to represent the total amount she will spend at the store.

Answers

Answer:

2.75c +3.59

Step-by-step explanation:

She only needs one bag of flour so it is a constant 3.59. She needs multiple bags of chocolate chips which is unknown so that will be c times the 2.75 for each bag

The wire supporting the tower makes a 25° angle of elevation with the ground. If the wire is attached to the ground 50 feet from the base of the tower, how tall is the tower

Answers

Check the picture below.

Make sure your calculator is in Degree mode.

In rectangle KLMN, KM = 9x+26 and LN = 84.5. Find the value of x.

Answers

Answer:

x = 6.5

Step-by-step explanation:

square is rectangle

9x+26 = 84.5

84.5 - 26 = 58.5

9x = 58.5

x = 58.5 divided by 9

x = 6.5

3
Suppose that a very la: Enter your search term
cameras and that of them are defective. A sample of 2 cameras is
8
selected at random. Define the random variable X as the number of defective cameras in the sample.
a. Write the probability distribution for X. Round to two decimal places.
X
P(X)
b. What is the expected value of X? Round to two decimal places.
Preview

Answers

Answer:

you were present when a senor student bullied a junior one. describe what happened to the teacher on duty



A -Domain: all numbers from 0 to 85. Range: all numbers from 0 to 14

B -Domain: whole numbers only from 0 to 14. Range: whole numbers only from 0 to 85.

C -Domain: all numbers from 0 to 14. Range: whole numbers only from 0 to 85.

Answers

Step-by-step explanation:

Notes:

The domain represents all x-values.

The range represents all y-values.

Domain: Whole numbers to represent the graph.

Range: Whole numbers to represent points.

A and C are incorrect.

A has the incorrect domain and range.

C represents all whole numbers and all real numbers.

B is correct.

Why?

B represents the whole numbers for where the line has been for x (0 - 14).

B represents the whole numbers for where the lines have been at for y (0 - 85)

B represents that the graph has ended.

Ann wants to set up chairs in rows of 8. If she sets 14 rows, how many seats will she have?

Answers

Answer:

112

Step-by-step explanation:

8×14 if each row has 8 chairs, and there's 14 rows that means 8×14 which equals 112 :)

Answer:

14 x 8=112

8 chairs are row multiply by the of rows

Two water balloons were launched into the air at different moments and collided. The water balloons were modeled by the quadratic functions: y=-7x2 + 26x + 6 and
y=-6x2 + 25x + 4 where y represents the height in meters and x represents the time in seconds after the launch. What is the time in seconds that the balloons
collided at the highest point?
O 1.75 seconds
O 20 seconds
O2 25 seconds
O 2.5 seconds

Answers

The time in seconds that the balloons collided at the highest point is; B: 2.0 seconds

What are quadratic equations?

We are told that the water balloons were modeled by the quadratic functions:

y = -7x² + 26x + 6 and y = -6x² + 25x + 4

where;

y = the height in meters

x = the time in seconds after the launch

The time at which they will collide has to be at the same height.

Thus;

-7x² + 26x + 6 = -6x² + 25x + 4

Rearranging this gives;

x² - x - 2 = 0

Using online quadratic equation solver gives us x = 2 or -1. We will take the positive one as x = 2.0 seconds

Read more about quadratic equations at; https://brainly.com/question/1214333

Answer:

the answer is 2.0 seconds

Step-by-step explanation:

I just took the test:)

F(x)x^2-x+3 find f(x+2)

Answers

Answer: =7

Step-by-step explanation:

a
triangle
The measure of the First angle of
is 25 degree less than the measure of the
Second angle. The measure of the third angle
of the triangle is triple the measure of the
second angle.

Answers

Alright, lets say the measure of the 3rd angle (the smallest one) is  x degree, then measure of the 1st angle will be (x + 25) degree, and 2nd one: 3x degree. The sum of all the angles in any triangles is 180 degrees.

(x + 25) + 3x + x = 180

5x + 25 = 180 ---> 5x = 180 - 25 ---> 5x = 155 ---> x = 155/5 ---> x = 31o (third angle)

31 + 25 = 56o (first angle)

3 × 31 = 93o (second angle)

56 + 93 + 31 = 180

The price of an item yesterday was $140 today the price is $343 what’s the percentage increase

Answers

Answer:

145% increase

Step-by-step explanation:

1)  343 - 140 = 203

2) 203/140 = 1.45

3) 1.45 x 100 = 145

Use the zero product property to find the solutions to the equation x2 -x-6 = 0.
X = -3 or x =-2
x X = -3 or x = 2
X =-2 or x = 3
X=2orx=3


Answer-----> C

Answers

Answer:

[tex]x = 3, -2[/tex]

Step-by-step explanation:

1: factor

[tex](x-3)(x+2)[/tex]

2: check

[tex]x^2 + 2x -3x -6[/tex]

3: solve for x

[tex]x = 3, -2[/tex]

Answer:

correct thank you

Step-by-step explanation:

?????????? WHAT ??????????

Answers

The area of square’s formula is length x length= answer^(2)
Or
Length^(2) = answer
Don’t forget to add the unit

Answer:

Side of the square (a) = 3½ = 7/2 m

Area of the square

= a²

= (7/2)²

= 49/4

= 12.25 m²

Hope it helps ⚜

What is 48(2)+1=

Please answer

Answers

Answer:

97

Step-by-step explanation:

48 ( 2 )

= 48 x 2

= 96

48 ( 2 ) + 1

= 96 + 1

= 97

Answer:

97

Step-by-step explanation:

Given the following question:

[tex]48(2)+1[/tex]

In order to find the answer, we apply the rule where 48(2) = 48 × 2

[tex]48(2)+1[/tex]
[tex]48(2)=48\times2[/tex]
[tex]48\times2=96[/tex]
[tex]96+1[/tex]
[tex]96+1=97[/tex]
[tex]=97[/tex]

Hope this helps.

Other Questions
Please answer this (who ever answers correctly gets brainlest) I really need help Really Fill in the blank with the word or phrase that best completes the sentence.Puer____.vocatus sumvocatus esvocatus estvocaus sunt Help It's mokeys meth PLS PLS PLS PLS HELP ASAPPPP Consider the following expression and determine which statements are true.\dfrac{7}{r}+2^3+\dfrac{s}{3}+11 r7 +2 3 + 3s +11start fraction, 7, divided by, r, end fraction, plus, 2, cubed, plus, start fraction, s, divided by, 3, end fraction, plus, 11Choose 2 answers:Choose 2 answers:(Choice A)AThe entire expression is a sum.(Choice B)BThe coefficient of sss is 333.(Choice C)CThe term \dfrac{7}{r} r7 start fraction, 7, divided by, r, end fraction is a quotient.(Choice D)DThe term 2^32 3 2, cubed has a variable. If you intercept a message that has been encrypted using a Caesar Cipher, what is the maximum number of times you would need to guess-and-check different keys for the cipher before cracking it CauseEffectThe Republic of Chinais established?O A. Mongolian rebels win their independence from China,B. Chinese communists and nationalists struggle for power.O C. Supporters of the Qing dynasty flee to Taiwan.O D. Great Britain forces China to accept the opium trade.SUBMITPREVIOUSHelp Recommend two practical ways in which high or secondary schools can assist learners or candidates with their career decisions Arun bought a pair of skates at the sale where the discount given was 20%. If the amount he pays is 1600 find the marked price Por qu razn dej el escudero su tierra natal y sevino a Toledo? Qu intencin critica observas eneste episodio? Which of the following are coefficients you could use in a balanced equation? (select all that apply). You have just been told to get your project done sooner. After a few conversations, you have overtime approved and need to set it up in your project. Which tip should you consider when adding overtime in Project How did the rebels' grievances indicate a breakdown in the newly constituted political processes? How did they indicate an erosion in social and political deference? Solve (-7/3)x -3=-53 this is math please help me Write an en expression that could be used to find the amount Samantha earns working any number of months, m. A graph illustrating the pressure and volume changes during one heartbeat is called the __________. Once you have identified the authors claim and also located all of the evidence provided, how do you analyze the claim?Decide if the evidence supports the claim well enough to convince most readers that its true.Decide how the author should have supported the claim, instead of the way he or she chose.Decide if the author should have done more research or worded the claim differently.Decide whether or not you agree with the authors claim, regardless of the evidence. How is market demand affected by price?