An isotope of lead, 201Pb, has a half-life of 8.4 hours. How many hours ago was there 70% more of the substance? (Round your answer to one decimal place.) hr

Answers

Answer 1

Step-by-step explanation:

half life time-50%-8.4hr

so for 10%- 8.4/5=1.68 hr

now for 70%

1.68 × 7 = 11.76 hrs

to one decimal place - 11.8hrs

Answer 2

11.8 hours ago, there were 70% more of the substance if an isotope of lead has a half-life of 8.4 hours.

What is half-life?

Half life is the time that it takes for half of the original value of some amount of a radioactive element to decay.

Half-life period - 50% -8.4hours

so for 10%- 8.4/5 = 1.68 hour

now for 70%

1.68 × 7 = 11.76 hours

To one decimal place - 11.8hours

Hence, 11.8hours is the answer.

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Related Questions

plz help me i need help

Answers

4 x 10^-7 x 2 = 8 x 10^-7
Therefore, 2 times as long.
Answer = 2 times as longer

Explanation:

8 x 10^-7 = (2)4 x 10^-7

How many units away is 1 from -6 on a number line?

Answers

Answer:

7 units

Step-by-step explanation:

(number line:)

<- -10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ->

                                       ←

         there are 7 units from 1 to -6 (you don't count the 0)

(I'm not sure if you understood my explanation, but I do am sure about the answer, so if there is something you didn't understand let me know, and which part are you confused about so I can help you out!)

Answer:

[tex]\huge\boxed{\sf 7\ units}[/tex]

Step-by-step explanation:

To find that how much far they are from each other, we can subtract both of them.

=> 1 - (-6)

=> 1 + 6

=> 7 units

So, they are 7 units apart from each other.

what is the first step to solving this problem: 3x-10=2(x+3)

Answers

Answer:

x = 16

Step-by-step explanation:

3x - 10 = 2(x+3)

First step is solve this:

2(x+3) = 2*x + 2*3 = 2x + 6

then:

3x - 10 = 2x + 6

3x - 2x = 6 + 10

x = 16

Check:

3*16 - 10 = 2(16+3)

48 - 10 = 2*19 = 38

Answer:

x = 16

Step-by-step explanation:

you start off by isolating the variable

Drag the tiles to the correct boxes to complete the pairs.
The tables show proportional relationships between x and y. Match each table with its constant of proportionality.
ху
ху
ху
ху
1 10
4 20
215
1
4
2 20
8 40
430
2
8
330
12 60
645
312
4
15

Answers

Answer:

can you send a picture please? i have no clue how to answer this. it seems confusing with the numbers


what is the questions .......

What is the area of triangle PQR to the nearest tenth of a square meter? Drawing is not to scale. A. 24.1 m2 B. 34.4 m2 C. 48.2 m2 D. 68.8 m2

Answers

Answer:

b

Step-by-step explanation:

The area of triangle PQR which is an SAS triangle, to the nearest tenth, is: A. 24.1 m²

What is the Area of an SAS Triangle?

The area of an SAS triangle = ½ × bc × sin(A).

Given the following:

PQ (b) = 14 mRQ (c) = 6 mAngle Q (A) = 35°

Area of triangle PQR = ½ × (14)(6) × sin(35)

Area of triangle PQR = 24.1 m²

Learn more about the area of an SAS triangle on:

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4x = 2x + 2x + 5(x-x) does this have one solution, no solution or infinite solutions

Answers

Answer:

infinite solutions

Step-by-step explanation:

4x = 2x + 2x + 5(x-x)

Simplify

4x = 2x + 2x + 5*0

4x = 2x + 2x

4x = 4x

Divide by x

4 =4

This is always true so this has infinite solutions

Answer: Infinite solutions

attachment help for question c no explanation only answer thank you

Answers

Answer:

Tablets.

Step-by-step explanation:

You didn't want an explanation so....here you go....no explanation.

Hope that helps and maybe earns a brainliest.

Have a great day!

the answer is

tablets

Drag each object to show whether distance is proportional to time in the situation represented.

Answers

Answer: please find the answer in the explanation.

Step-by-step explanation:

1.) The distance is not proportional to time. Because the distance was constant from time = 3 seconds to 10 seconds.

2.) A person running down a field to score a touchdown. Not enough information.

3. A dog jogging at a constant speed for 20 minute. The distance is proportional to time because of the constant speed.

4.) The distance is proportional to time because their is increase in distance covered and increase in time taken.

5.) A truck passing through the 4 cities at a constant speed. The distance is proportional to time because the speed is constant.

6.) A horse running around a race track. Distance is not proportional to time because this is not a linear motion.

Please help! Dad will murder me if I don't have this done by the time he gets home! 100 points for whoever solves this!

Answers

Answer:

3(4)to the 3

Step-by-step explanation:

Evaluate 9x*2 y*−2 for x = –3 and y = 2. Answers:

Answers

Answer:

20 and 1/4.

Step-by-step explanation:

9x^2 * y^(-2), for x = -3 and y = 2.

9(-3)^2 * 2^(-2)

= 9 * 9 * (1/4)

= 81 * 1/4

= 81 / 4

= 20.25

= 20 and 1/4.

Hope this helps!

Answer:

Step-by-step explanation:

Let's fill the values in.

9(-3)*2(2)*-2

Using PEMDAS, we would first multiply the two numbers where x and y used to be.

-27 * 4 * -2

Now we would finish multiplying this.

216.

Hope this helps!! <3

Which statement best compares the two functions?



The minimum of function A occurs 1 unit higher than the minimum of function B.


The minimum of function A occurs 3 units higher than the minimum of function B.


The minimum of function A occurs 5 units lower than the minimum of function B.


The minimum of function A occurs 7 units lower than the minimum of function B.

Answers

Answer:The minimum of function A occurs 1 unit higher than the minimum of function B.

Step-by-step explanation:

Answer:

D

Step-by-step explanation:

Trust

The five-number summary for the number of touchdowns thrown by each quarterback in the British Football League is shown in the following table. About what per cent of quarterbacks in the British Football League threw more than 13 touchdowns?

Answers

Answer:

25%

Step-by-step explanation:

Answer:

25%

Step-by-step explanation:

PLEASE HELP ME!! I WILL GIVE BRAINLIEST!!

Find the output, y, when the input, x, is -5.

Answers

Answer:

[tex]\boxed{y = -2}[/tex]

Step-by-step explanation:

Hey there!

To find y when x is -5 we go to -5 on the x-axis.

When at -5 find where the blue line is vertical to -5,

which is -2.

Hope this helps :)

The Answer is:

y = - 2

which of these expressions are equivalent to p/3?

A. p-2/3

B. 1/3p

C. p-3

D. 3/p

E. 3p/p

Answers

Answer: Choice B.  1/3p

This is assuming that p is not in the denominator. To make it more clear that p is not in the denominator, I recommend you write (1/3)p.

Taking 1/3 of a number is the same as dividing by 3.

Example:

27/3 = 9

27*(1/3) = 9

1/3p

This is expressed as equívalent because 1/1 = 1 this 1/3=.33, thus 1/3 is p/3

Use the method of cylindrical shells to find the volume V generated by rotating the region bounded by the given curves about the specified axis.

y = 6x − x2, y = 8; about x = 2

Answers

Answer:

[tex]\mathbf{V = [\dfrac{ 8 \pi }{3}] }[/tex]

Step-by-step explanation:

Given that:

y = 6x - x² , y = 8  about  x = 2

To find the volume of the region bounded by the curves about x = 2; we have the radius of the cylindrical shell to be x - 1, the circumference to be 2 π (x -2 ) and the height to be 6x - x² - 8

6x - x² - 8

6x - x² - 8 = 0

-x² + 6x - 8 = 0

x² - 6x + 8 = 0

(x -4) (x - 2  ) = 0

So;

x = 2 , x = 4

Thus, the region bound of the integral  are from a = 2 and b = 4

Therefore , the volume of the solid can be computed as :

[tex]V = \int \limits ^b _a \ 2x \times f(x) \ dx[/tex]

[tex]V = \int \limits ^4_2 2 \pi (x -2) (6x -x^2 -8) \ dx[/tex]

[tex]V = 2 \pi \int \limits ^4_2 (6x^2 - x^3 -8x -12 x - 2x^2 +16) \ dx[/tex]

[tex]V = 2 \pi \int \limits ^4_2 (8x^2 -x^3-20x +16) \ dx[/tex]

[tex]V = 2 \pi \int \limits ^4_2 ( -x^3+8x^2-20x +16) \ dx[/tex]

[tex]V = 2 \pi [\dfrac{ -x^7}{4}+\dfrac{8x^3}{3} -\dfrac{20x^2}{2} +16x]^4_2[/tex]

[tex]V = 2 \pi [\dfrac{ -(4^4-2^4)}{4}+\dfrac{8(4^3-2^3)}{3} -\dfrac{20(4^2-2^2)}{2} +16(4-2) ]^4_2[/tex]

[tex]V = 2 \pi [\dfrac{ -(256-16)}{4}+\dfrac{8(64-8)}{3} -10(16-4)} +16(2) ][/tex]

[tex]V = 2 \pi [\dfrac{ 4}{3}][/tex]

[tex]\mathbf{V = [\dfrac{ 8 \pi }{3}] }[/tex]

V = 8 pi / 3 ( pi “ 3.14 “ )

A shipping container in the shape of a rectangular prism is 60 feet long, 45 1/2 feet wide, and 14 feet tall. What is the volume of the shipping container? A. 2,400 ft.^3 B. 2,730 ft.^3 C. 38.220 ft.^3 D. 76,440 ft.^3 Please include work!!

Answers

C. 38,200 ft^3

Why you ask? Good question, how you solve volume is l•w•h=v (length•width•height=volume) so it was 60•45.5•14=38,200

Hope this helps!

The answer is 38,220.
You multiply the width, height, and length.
Width= 45 1/2
Height= 14
Length= 60

45 1/2•14•60= 38,220

Kaitlyn can build a shed in 6 days. Mark can build the same shed in 8 days. Which equation can be used to find d, the number of days it would take Kaitlyn and Mark to build the shed together? Rate (Sheds per Day) Time (Days) Fraction Completed Kaitlyn One-sixth d One-sixth dd Mark One-eighth d One-eighth dd One-sixth d minus one-eighth d = 48 One-sixth d + one-eighth d = 48 One-sixth d minus one-eighth d = 1 One-sixth d + one-eighth d = 1

Answers

Answer:

  One-sixth d + one-eighth d = 1

Step-by-step explanation:

When they work together, their rates of completion add. They want to build one shed, so the number of sheds being built is ...

  (Kaitlyn's sheds per day)×(days Kaitlyn works) +(Mark's sheds per day)×(days Mark works) = 1 shed

  (1/6)d + (1/8)d = 1 . . . . matches the last choice

the awnser would be 1

What is the value of f(1)?

Answers

Answer:

A function normally tells you what y is if you know what x is.

Inverses. A function normally tells you what y is if you know what x is. The inverse of a function will tell you what x had to be to get that value of y. A function f -1 is the inverse of f if. for every x in the domain of f, f -1[f(x)] = x, and.

Plzz help I’ll mark brainliest

Answers

Answer:

6cot 50

Step-by-step explanation:

Tan 50=6/x

x= 6/(tan 50)

x= 6cot 50°

Answer:

? = 6 cot 50

Step-by-step explanation:

Since this is a right triangle, we can use trig functions

tan theta = opp /adj

tan 50 = 6 /?

? tan 50 = 6

? = 6 / tan 50

We know that 1 / tan 50 = cot 50

? = 6 cot 50

a 20-foot flagpole casts a 6-foot Shadow how tall is a nearby building that casts a 30-foot shadow

Answers

The building would be 100ft tall. You have to take 20/6 = ?/30 The difference between 6 and 30 is x5. Then all you have to do is 20x5 and you get 100ft.

Answer :

The building would be 100ft tall. You have to take 20/6 = ?/30 The difference between 6 and 30 is x5. Then all you have to do is 20x5 and you get 100ft.

Evaluate the expression. *
23 – (12 + 6) + 8
Please help

Answers

Answer:

13

Step-by-step explanation:

23-(12+6)+8

23-18+8

31-18

13

answer is 13

Step-by-step explanation:

Using the BODMAS rule,bracket of division or multiplication, addition or subtraction.

This applies the rule:

therefore,

23- (12+6)+8 ,calculate within bracket first

=23-(18)+8

now remove the bracket,by multiply by the -1

=23-18+8

the start calculate from the left to right

=23-10

=13

therefore the answer is 13

5. The cost of movie tickets at the
Cinema Verite is 9 dollars for adults
and five dollars for children under 12.
During the Saturday and Sunday
matinees, adults are charged 8 dollars
for admission and children under 12
are charged 4 dollars. At any time at
all, there is a group discount for groups
of 15 or more adults at a cost of 6
dollars per ticket. What is the cost for 2
adults and 3 children during the
Saturday matinee?
a. 27
b. 28
C. 14
d. 32

Answers

Answer:

its 28 dude, because it says that adults and children are played more on saturday.(adults on Saturday=$8 and children under 12 are $4

B because more adults and children played on saturday.

Find the value of m∠ACD. A. 30º B. 15º C. 60º D. 90º

Answers

Answer:

A. 30 degrees

Step-by-step explanation:

Set the two angles equal to each other:

3x-15 = 45-x

Solve for x:

4x -15 = 45

4x = 60

x = 15

Finally, plug in the x to one of the equations (preferably 45 - x since it's easier to solve) and solve for x.

45 - 15 = 30

Answer:

A 30 degrees

Step-by-step explanation:

Solve the equation using the multiplication property of equality and the reciprocal of
1
4
.

1
4
( r −
5
2
) =
1
8

Answers

The answer is r=52.09

Please answer ASAP

Randomly pick 6 points from a square of side = 1. Show that you can always find 2 points from these 6 that their distance is less or equal to [tex]\frac{\sqrt{2} }{2} }[/tex]

Randomly pick 5 points from a sphere. Show that you can always find a closed semi-sphere ( half a sphere and boundary) that contains 4 points.

Answers

Problem 1.

My thinking is that the furthest you can get is have two points at each opposite corner, so the distance between them is sqrt(2). If we have two other points with this property, then all four corners are filled up. It is possible to pick two points where the distance is 1 unit.

Then a fifth point can be placed at the center such that the distance from it to any of the corners is sqrt(2)/2. We placed the fifth point at the center to try to get as far away as possible from the other four points.

Basically we're trying to find the worst case scenario (leading to the largest distance possible) and seeing how we can fill up the square. This establishes the upper bound. Any other kind of scenario will have a distance less than the upper bound.

===================================================

Problem 2.

For this one, I'm not sure what to make of it. The terminology is a bit strange so I'm not going to be fairly helpful here. Sorry about that.

If I had to guess, I'd assume it has something to do with the fact that a plane is uniquely defined by 3 points. That fourth point is not coplanar with the other three, which helps define the semi-spherical portion. The fifth point is just extra. The points can't be all collinear or else a plane won't form. Though to be honest, I'm still not sure about problem 2. I'd get a second opinion.

The answer above is correct


Calculate the surface area of a cube when the length of a side a = 15cm.
Surface area = 6a^2​

Answers

Answer:

[tex]\boxed{ \sf 1350 \ cm^2}[/tex]

Step-by-step explanation:

Surface area of a cube = 6a²

a = side length

The side length is given 15 cm.

[tex]6(15)^2[/tex]

[tex]6(225)[/tex]

[tex]1350[/tex]

The surface area of the cube is 1350 cm².

The surface area of the cube is 1350cm^2



Which statement BEST explains why the sine of an acute angle is equal to the cosine of the angles complement?

Answers

Answer:

In a right triangle, the sine of one acute angle, A, equals the cosine of the other acute angle, B. Since the measures of these acute angles of a right triangle add to 90º, we know these acute angles are complementary. ∠A is the complement of ∠B, and ∠B is the complement of ∠A.

Step-by-step explanation:

is there any answer choices i can see? :)

Find the surface area and volume of the following figures.

Answers

White figure Area = 128[tex]\pi[/tex]

White surface area = appro. 301

Yellow area = 320[tex]\pi[/tex]

Yellow Surface area = approx. 653

Area found with = 2πrh+2πr2

Surface Area found with = 2πrh+2πr2

You need to memorize them for tests

Hope that helped!!! k

There a hinded message Jeff

Please help me on this question

Answers

Answer:

The area can be expressed as: [tex]\pi r^2+lw[/tex].

We have l=10, because 18-2(4)

We have w=8, as given.

Thus, the rectangle area is 80.

There are two semicircles, but they add to form a full circle, which makes things a lot easier. We have the circle area formula, and substituting the values gives us 50.24 as the circle volume

80+50.24=130.24.

Rounded to 1 decimal place that is 130.2

Hope this helps :)

(08.01) Two lines, A and B, are represented by the following equations: Line A: y = x − 1 Line B: y = −3x + 11 Which of the following options shows the solution to the system of equations and explains why? (3, 2), because the point does not lie on any axis (3, 2), because one of the lines passes through this point (3, 2), because the point lies between the two axes (3, 2), because both lines pass through this point

Answers

Answer:

the answer is D

Step-by-step explanation:

y=x-1

2=3-1

2=2

y=-3x+11

2=-3(3)+11

2=-9+11

2=2

Answer:

Step-by-step explanation:

If both lines pass through the point (3, 2), we automatically know that (3, 2) is the soution of the system of linear equations given here, AND that (3, 2) is a solution of equation A and equation B both.

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