If the radioactive half-life of a substance is 20 days, and there are 5 grams of it initially. When will the amount left be 2 grams? Round to the nearest tenth of a day.

Answers

Answer 1

Answer: [tex]26.4\ \text{days}[/tex]

Step-by-step explanation:

Given

Half life of radioactive substance is [tex]T_{\frac{1}{2}}=20\ \text{days}[/tex]

Initial amount [tex]A_o=2\ \text{days}[/tex]

Amount left at any time is given by

[tex]\Rightarrow A=A_o2^{\dfrac{-t}{T_{\frac{1}{2}}}}\\\\\Rightarrow 2=52^{\dfrac{-t}{20}}\\\\\Rightarrow 0.4=2^{\dfrac{-t}{20}}\\\\\Rightarrow 2^{\dfrac{t}{20}}=2.5\\\\\Rightarrow \dfrac{t}{20}\ln 2=\ln (2.5)\\\\\Rightarrow t=\dfrac{20\ln (2.5)}{\ln 2}\\\\\Rightarrow t=26.4\ \text{days}[/tex]

It takes 26.4 days to reach 2 gm.


Related Questions

The probability of drawing a red candy at random from a bag of 25 candies is 2/5. After 5 candies are removed from tehe bag, what is the probability of randomly drawing a red candy from the bag?

Answers

Given:

The probability of drawing a red candy at random from a bag of 25 candies is [tex]\dfrac{2}{5}[/tex].

To find:

The probability of randomly drawing a red candy from the bag after removing 5 candies from the bag.

Solution:

Let n be the number of red candies in the bag. Then, the probability of getting a red candy is:

[tex]P(Red)=\dfrac{\text{Number of red candies}}{\text{Total candies}}[/tex]

[tex]\dfrac{2}{5}=\dfrac{n}{25}[/tex]

[tex]\dfrac{2}{5}\times 25=n[/tex]

[tex]10=n[/tex]

After removing the 5 candies from the bag, the number of remaining candies is [tex]25-5=20[/tex] and the number of remaining red candies is [tex]10-5=5[/tex].

Now, the probability of randomly drawing a red candy from the bag is:

[tex]P(Red)=\dfrac{5}{20}[/tex]

[tex]P(Red)=\dfrac{1}{4}[/tex]

Therefore, the required probability is [tex]\dfrac{1}{4}[/tex].

Simplify the expressions by combining like terms.
30) 4x + 3-x =

Answers

Step-by-step explanation:

the answer is -1. I have a picture, take a lot at it

Answer: 3x+3

Step-by-step explanation:

4x+3-x

= (4x-x) + 3

= 3x+3

Confirm that f and g are inverses by showing that f(g(x)) = x and g(f(x)) = x.

f(x) = 4/x
g(x) = 4/x

Answers

Answer:

Hello,

Step-by-step explanation:

[tex]f(x)=\dfrac{4}{x} \\\\g(x)=\dfrac{4}{x} \\\\\\(gof)(x)=f(g(x))=f(\dfrac{4}{x} )=\dfrac{4}{\dfrac{4}{x} } =\dfrac{4*x}{4} =x\\\\\\(fog)(x)=g(f(x))=g(\dfrac{4}{x} )=\dfrac{4}{\dfrac{4}{x} } =\dfrac{4*x}{4} =x\\[/tex]

Select the correct answer. Consider this system of equations, where function f is quadratic and function g is linear:

y = f(x)

y = g(x)



Which statement describes the number of possible solutions to the system?

A. The system may have no, 1, 2, or infinite solutions.

B. The system may have no, 1, or infinite solutions.

C. The system may have 1 or 2 solutions.

D. The system may have no, 1, or 2 solutions

Answers

Answer:

C is the answer

Step-by-step explanation:

Quadratic equations have at most 2 solution, and linear equations only have 1 solution, and since y is equal to both of them, it can only have 1 or 2 solutions.

The correct answer is option D.  The system may have no, 1, or 2 solutions

What is quadratic equation?

A quadratic equation is a second-order polynomial equation in a single variable x , ax²+bx+c=0. with a ≠ 0 .

f(x) is a quadratic function and g(x) is linear function

y=f(x)

y=g(x)

Quadratic equations have at most 2 solution

linear equations only have 1 solution,

f(x)=g(x)=y

y is equal to both of them, it can only have 1 or 2 solutions.

A line and a parabola can intersect zero, one, or two times

Therefore, a linear and quadratic system can have zero, one, or two solutions

Hence, the correct answer is option D.  The system may have no, 1, or 2 solutions

To learn more on Quadratic equation click:

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a car can complete journey of 300 km with the average speed of 60 km per hour how long does it take to complete the journey what is the speed of the car if it covers only 200 km in the same interval of the time
please I need help urgent ​

Answers

Answer:

a. 5 hours

b. 40 kph

Step-by-step explanation:

300 km ÷ 60 km = 5 hours

200 km ÷ 5 hours = 40 kilometers per hour

Convert the 7pi/5 to a degree measure

A=252
B=504
C=792
D=75

Answers

Answer:

252

Step-by-step explanation:

The conversion factor is

180/pi

7pi/5 * 180/pi = 7 *180/5 = 252 degrees

If I have 180$ and a pack of dvds cost 18 how much can I buy

Answers

Answer:

10 packs of dvds

Step-by-step explanation:

$180 / $18 = 10 packs

You can buy a maximum of 10 dvd packs

Answer:

you can buy 10 dvds that is thr answer

find the x- and y-intercept of the graph of -9x+7y=27 . State tour based as a whole number of as a improper fraction in simplest form

Answers

answer:

is this cool? or explanation?

A tank contains 150 liters of fluid in which 20 grams of salt is dissolved. Brine containing 1 gram of salt per liter is then pumped into the tank at a rate of 5 L/min; the well-mixed solution is pumped out at the same rate. Find the number A(t) of grams of salt in the tank at time t.

Answers

Answer:

the number A(t) of grams of salt in the tank at a time is A(t)=150-110e-t/50

Sam ordered 2 tons of crushed stone. How many pounds of crushed stone does she have?

Answers

Answer:

4000

Step-by-step explanation:

1 ton = 2000 pounds

2 tons = ? pounds

Multiply:

2000 × 2 = 4000

There will be 4000 pounds of crushed stone.

Hope this helped.

G I V E N :

Sam ordered 2 tons of crushed stone. How many pounds of crushed stone does she have?

S O L U T I O N :

Here, we need to convert the tons into pounds to get the desired result

According to the question :

We know that,

1 ton = 2000 pounds

2 tons = 2(1000 pounds) = 2000 pounds

Hence, she have 2000 pounds of crushed stone

A regular polygon has exterior angles of 60°
What is the sum of the polygon’s interior angles?

Answers

Answer:

720°

Step-by-step explanation:

The sum of the exterior angles of a polygon = 360°

Divide by 60 to find number of sides (n)

n = 360° ÷ 60° = 6

The sum of the interior angles of a polygon is

sum = 180° (n - 2) ← n is the number of sides

Here n = 6 , then

sum = 180° × 4 = 720°

The sum of the exterior angles of a regular polygon is 360º

Each exterior angle of a regular polygon is 60º/n

360º/n=60º

360/60=n

6=n

A polygon with 6 sides is a hexagon.

Use the formula (n-2)×180

(6-2)*180=4*180=720º

another solution...

you have 6 interior angles (hexagon)

if an exterior angle is 60º, the corresponding interior angle is 180-60=120º

you have 6 of these 120º angles

6*120=720º

Algunos granos de maíz al ser calentados revientan y pierden agua de manera explosiva.
En promedio se puede considerar que tienen una masa de 125 mg y cuando explotan (palomitas
de maíz) su masa es de 106 mg. ¿Cuántos granos de maíz pira se requerirán para obtener una
libra de palomitas de maíz?

Answers

Answer:

Step-by-step explanation:

4280 granos de maíz pira se requerirán para obtener una libra de palomitas de maíz.

Cálculo

Dado que algunos granos de maíz al ser calentados revientan y pierden agua de manera explosiva, y en promedio se puede considerar que tienen una masa de 125 mg y cuando explotan (palomitas de maíz) su masa es de 106 mg, para determinar cuántos granos de maíz pira se requerirán para obtener una libra de palomitas de maíz se debe realizar el siguiente cálculo:

453592 mg = 1 lb453592 / 106 = X4279.16 = X

Por lo tanto, 4280 granos de maíz pira se requerirán para obtener una libra de palomitas de maíz.

Aprende más sobre cálculo en https://brainly.com/question/2193984

plz help me ans fast for 10 pts​

Answers

Answer:

universal set is the right answer

Solve for a.
-4a – 2a – 7 = 11
a =
[?]

Answers

Answer:

a = [-3]

Step-by-step explanation:

-4a - 2a - 7 = 11

Combine like terms

-4a - 2a = -6a

-6a - 7 = 11

Add 7 to both sides

-6a = 18

Solve for a

a = 18/-6
••••••••••••••••••••••••••••••
doomdabomb:
All brainliest and thanks
are appreciated and
would mean a lot to me,
thanks!

a = -3
••••••

Answer:

or, -4a - 2a -7 = 11

or, -4a -2a =11 +7

or, - 6a = 18

or, a= 18÷ -6

a= -3

helphelphelphelphelphelphelp

Answers

Answer:

P = 1,-10

Q=1,-1

R=7,-1

S=7,-10

which algebraic expression represents this word description the quotient of six and the sum of a number and eight

Answers

6/x+8

Step by step explanation: Quotient means that you are dividing one term by another, so from this expression you would get that 6 is being divided by x (unknown variable) + 8

I just need the numbers anyone help ?

Answers

From (-2, 4) you’re going to go up 2 to the right 5. Then go down 2 left 5

Answer:

See below & pic.

Step-by-step explanation:

Start by plotting the given point. Then use the slope to find two more points. From the given point go up 2 and right 4. GO back to the given point. Go down 2 and left 4. Now you have 3 points. Connect them with a line.

Solve for x.
3x + 2
2x + 6
x = [?]

Answers

Answer:

4

Step-by-step explanation:

Im assuming you mean the first and second equation equal each other:

3x+2=2x+6

x=4

Can you please answer this answer with a step by step explanation?

the BEST answer gets the BRAINLIEST answer mark!​

Answers

Answer:

Step-by-step explanation:

If K is square number, then exponents in number N are even.

Geometry, please answer question ASAP

Answers

Answer:

I'm going to say A and B (I think)

TWO TEST
23. Evaluate 4b2 for b
= -1/2

Answers

4b² when b = -1/2

[tex] = {4( \frac{ - 1}{2})}^{2} \\ = 4( \frac{1}{4}) \\ = \frac{4}{4} \\ = 1[/tex]

Answer:

-4

Step-by-step explanation:

4b x 2 when b = -1/2

1) put -1/2 where b is.

4 x -1/2 x 2

2) solve.

-2 x 2

-4

rationalise the denominator of 2sq3+3sq2/4sq3+sq2​

Answers

Answer:

[tex]\frac{9+5\sqrt6}{23}[/tex]

Step-by-step explanation:

We can rewrite the fraction as

[tex]\frac{2\sqrt{3}+3\sqrt{2}}{4\sqrt{3}+\sqrt{2}}[/tex]

In order to rationalize the denominator of such a complex fraction, we must multiply the fraction by the conjugate of the denominator. In this case, the conjugate of the denominator would be [tex]4\sqrt{3}-\sqrt{2}[/tex]. Multiplying both sides of the fraction by the conjugate of the denominator would result in the fraction:

[tex]\frac{9+5\sqrt6}{23}[/tex]

Please help with this question

Answers

Answer:

-3.662rad × 180/π = -209.8°

Step-by-step explanation:

Answer:

1 degree = .01745329 radians

1 radian = 57.2957877856 degrees

-209.8 degrees = .01745329 * -209.8 =

-3.66170024200 radians

Step-by-step explanation:


The access code for a cars security system consists of 4 digits. The first digit cannot
be 0 and the last digit nust be even. How many different codes are available?

Answers

Answer:

4500

Step-by-step explanation:

The first digit can't be 0. so it will be a number from 1000 to 9999. That's a total of 9000 numbers (9999-1000+1=9000). Since the last digit must be an even number that is one half of the 9000 numbers which is 4500.

Evaluate: 2-4 А. =100 В. -8 ОО С. -16 D. 1 16​

Answers

Answer:

D. 1/16

Step-by-step explanation:

Evaluate: 2^-4

А. =100

В. -8ОО

С. -16

D. 1/16

Given

2^-4

= 1 / 2⁴

= 1 / (2 * 2 * 2 * 2)

= 1 / 16

Therefore,

2^-4 = 1/16

D. 1/16

Could someone please help me out?

Answers

Answer:

4.5

Step-by-step explanation:

let,

k×9²=300

k = 300/81

or, k = 100/27

as two triangles are similar,

if smaller triangle's corresponding side is x (let), then,

kx²=75

100x²/27=75

x²=75×27/100

x=√81/4

x=9/2

x=4.5

Consider this equation. tan) 19 17 If 8 is an angle in quadrant II, what is the value of Cos() OA. 19 6 OB. 17 6 O c. V18 6 OD. 17​

Answers

Using trigonometric identities, it is found that the value of [tex]\cos{\theta}[/tex] is given by:

B. [tex]\cos{\theta} = \frac{\sqrt{17}}{6}[/tex]

What is the tangent of an angle?

It is given by the division of it's sine by it's cosine, that is:

[tex]\tan{\theta} = \frac{\sin{\theta}}{\cos{\theta}}[/tex]

In this problem, the equation given is:

[tex]\tan{\theta} = -\sqrt{\frac{19}{17}}[/tex]

That is:

[tex]\frac{\sin{\theta}}{\cos{\theta}} = -\sqrt{\frac{19}{17}}[/tex]

[tex]\sin{\theta} = -\sqrt{\frac{19}{17}}\cos{\theta}[/tex]

The following identity is applied:

[tex]\sin^2{\theta} + \cos^2{\theta} = 1[/tex]

Then:

[tex]\left(-\sqrt{\frac{19}{17}}\cos{\theta}\right)^2 + \cos^2{\theta} = 1[/tex]

[tex]\frac{36}{17}\cos^2{\theta} = 1[/tex]

[tex]\cos^2{\theta} = \frac{17}{36}[/tex]

[tex]\cos{\theta} = \frac{\sqrt{17}}{6}[/tex]

More can be learned about trigonometric identities at https://brainly.com/question/24496175

Answer:

Hi sorry I just wanted to ask is it B or D? positive or negative?

Step-by-step explanation:

edmentum is the worst

If lines AB and CD are paralell, which of the following statements is true? Check All That Apply​

Answers

Answer:

D and E is the answer..

Step-by-step explanation:

nothing to explain .. D has the symbol of parallel.. and all parallel lines are coplaner

The correct answers are option D and option E that is AB || CD and the lines AB and CD are coplanar.

What are parallel lines?

The lines which do not intersect each other at any point they can only intersect at infinity are called parallel lines. All the parallel lines are coplanar to each other.

From the above explanation, the parallel lines are represented as AB || CD and also coplanar to each other.

Therefore the correct answers are option D and option E that is AB || CD and the lines AB and CD are coplanar.

To know more about parallel lines follow

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We have two fractions, 3/4 and 7/6 , and we want to rewrite them so that they have a common denominator (and whole number numerators). What numbers could we use for the denominator?

Answers

Answer:

12,24 etc

Step-by-step explanation:

4 and 6 both go into 12 evenly

4*3 = 12

6*2 = 12

12 is the least common denominator

We could also use 24

4*6 = 24

It is a common denominator, but not the least common denominator

We can use any multiple of 12

arrange0.2,¼,30%,10%in ascending and descending order​

Answers

Answer:

Ascending- 10%, 0.2, 1/4, 30%

Descending- 30%, 1/4, 0.2, 10%

Step-by-step explanation:

0.2 = 2/10 = 4/20

1/4 = 5/20

30% = 30/100 = 6/20

10% = 10/100 = 2/20

Ascending

-2/20, 4/20, 5/20, 6/20

- 10%, 0.2, 1/4, 30%

Descending

- 6/20, 5/20, 4/20, 2/20

- 30%, 1/4, 0.2, 10%

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