A sample of radioactive element follows the law of exponential decay. if there are 50g of the element at noon 30g at 3:00 pm that same day then how many grams will there be at 9:00 pm that same day?​

Answers

Answer 1

Answer:

10.8 g

Step-by-step explanation:

Exponential decay equation:  [tex]A=A_0e^{-rt}[/tex]

[tex]A_0[/tex] is the initial amount (at time t = 0, "noon")

r is the decay rate

You have two pieces of information:

Noon   t = 0  [tex]A_0=50[/tex]

3:00 pm  t = 3  [tex]A=30[/tex]

Plug those in to get  [tex]30=50e^{-r(3)}[/tex]

Divide by 50.

[tex]0.6=e^{-3r}[/tex]

Take the natural log of both sides.

[tex]\ln(0.6)=-3r[/tex]

Divide by -3.

[tex]\frac{\ln{(0.6)}}{-3}=r\\\\r \approx .17027[/tex]

Now, for 9:00 pm, use this value of r and  t = 9.

[tex]A=50e^{-.17027(9)} \approx 10.8[/tex]


Related Questions

multiply 5/12 and the multiplicative inverse of -1/4​

Answers

Answer:

The answer is -2

Step-by-step explanation:

Hope it helps :)

Question 6 of 40
Multiply (x2 + 2x + 3)(4x2 – 2x + 1).
O A. 5x2 + 4
O B. 4x + 10x + 17x2 + 8x + 3
O C. 44 + 6x3 + 9x2 - 4x + 3
O D. 44 - 4x2 + 3

Answers

The answer is C. Multiply the second parentheses by each term from the first parentheses, Distribute through the parentheses and collect like terms.

4. Choose the expression that matches the following statement: three times the difference of
two times a number and 7 taken from 8 of a number.
a) 2x+21
b) 2x - 21
c) -2x - 21
d) -2x - 7

Answers

i think the answer is b

If the radius is 10 ft, what will be the area of the circle!

Answers

Answer:

314

Step-by-step explanation:

Formula for area -> A= PI times radius squared

10x10=100x3.14+314

Answer:

314.16ft

Step-by-step explanation:

Diameter = 2  

×

Radius

Diameter = 2

×

10

Diameter = 20 feet

Write three ratios that are equivalent to 75% and three
ratios that are equivalent to 100%.

Answers

The three ratios that are equivalent to 75% are 75/100, 15/20 and 3/4  and the three ratios that are equivalent to 100% are 100/100, 20/20, and 4/4.

What is ratio?

A ratio in mathematics demonstrates how many times one number is present in another. For instance, if a bowl of fruit contains eight oranges and six lemons, the ratio of oranges to lemons is eight to six. The ratio of oranges to the total amount of fruit is 8:14, and the ratio of lemons to oranges is 6:8.

First we have to write the equivalent ratios for 75%.

Since, 75% can be written as,

75/100

Simplifying this, 15/20

Again simplifying this, 3/4

Hence, the three ratios that are equivalent to 75% are 75/100, 15/20 and 3/4.

Now to write the equivalent ratios for 100%.

Since, 100% can be written as,

100/100

Simplifying this, 20/20

Again simplifying this, 4/4

Hence, the three ratios that are equivalent to 100% are 100/100, 20/20, and 4/4.

Therefore,  the three ratios that are equivalent to 75% are 75/100, 15/20 and 3/4  and the three ratios that are equivalent to 100% are 100/100, 20/20, and 4/4.

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A town has a population of 18000 and grows at 2% every year. What will be the population after 11 years, to the nearest whole number?

Answers

Answer:

~22381

Step-by-step explanation:

a=starting value = 18000

r=rate = 2%=0.02

Exponential Growth:

b=1+r=1+0.02=1.02

b=1+r=1+0.02=1.02

Write Exponential Function:

y=18000(1.02)^x

y=18000(1.02)

x

Put it all together

\text{Plug in time for x:}

Plug in time for x:

y=18000(1.02)^{11}

y=18000(1.02)

11

Evauate:

y= 22380.73755

y=22380.73755

Round:

y\approx 22381

y≈22381

Toby buys packs of 12 racing cars for R49,99 and sells each racing car for R10 at school
1.1 Determine the cost price per racing car
1.2 calculate the profit toby makes per racing car
1.3 Determine toby's profit margin on one pack 12 racing car

Answers

Answer:

1.1  R5.83

1.2 R70.01

1.3 58.34%

Step-by-step explanation:

Given that he buys a pack of 12 racing cars  for  R49,99 then the unit cost for a car which is the total cost divided by the number of cars in a pack

= R49,99/12

= R4.17

If each car is sold for R10 then the profit made on each car which is the difference between the cost and the selling price

= R10 - R4.17

= R5.83

The profit margin on one pack of 12 racing cars

Profit margin is the ratio of the profit to the total selling price

The total profit (profit on one pack of 12 racing cars)

= R5.83 * 12

=R70.01

Total selling price = R10 * 12

=R120

Margin = R70.01 / R120

= 58.34%

Multiply the two fractions (1/2)(2/5). Simplify your answer.

A.2/7
B.1/5
C.20/100
D.2/10

Answers

Answer:

b

Step-by-step explanation:

Lee’s fish is 4 centimeters long.
Tia’s fish is 11 centimeters long.

Answers

Okayyy andddd what do u need answerd?
Tia’s fish is longer

For a given arithmetic sequence, the first term, 47, is equal to 26, and the 37 th term, a37, is equal to 278. th Find the value of the 4th term, a4.​

Answers

9514 1404 393

Answer:

  47

Step-by-step explanation:

Given:

  a1 = 26, a37 = 278

Find:

  a4

Solution:

Filling in the given values in the formula for the general term of an arithmetic sequence, we have ...

  an = a1 +d(n -1)

  a37 = 26 +d(37 -1) = 278

  d = (278 -26)/36 = 7 . . . . . . solve for d

Then the 4th term is ...

  a4 = 26 +7(4 -1)

  a4 = 47

The solution set of 12 x squared minus 14 x equals 10 is

Answers

The given quadratic equation has two possible roots as -

{x} = -1/2 and {x} = 1.667.

What is a quadratic equation?

A quadratic equation is a equation that is of the form -

y = f{x} = ax² + bx + c

Given is the statement as -

"12 x squared minus 14 x equals 10"

The given function can be written as -

f(x) = 12x² - 14x - 10

Refer to the graph attached. The x - intercepts show the solution of the given quadratic equation. So, we can write -

(x + 1/2)(x - 1.667) = 0

(x + 1/2) = 0     and     (x - 1.667) = 0

x = -1/2     and      x = 1.667

Therefore, the given quadratic equation has two possible roots as -

{x} = -1/2 and {x} = 1.667.

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Anna has 60 coins in her piggy bank. She notices that she only has dimes and pennies. If she has exactly four times as many pennies as dimes, how many pennies are in her piggy bank?

Answers

43 Penney’s and $6
43-6

Tell whether the angles are adjacent or vertical. Then find the value of x.

Answers

Answer is vertical and 128 degrees

Step by step

Vertical angles are opposite each other.
Vertical angles are congruent, or the same

3) Mr. Johnson uses 2.34 yards of yarn to knit a scarf. If Mr. Johnson has a total of 30.42 yards of yarn, how many scarfs will he be able to knit?​

Answers

she will be able to knit 13 scarfs

Solution

Given ,

Mr. Johnson uses 2.34 yards of yarn to knit a scarfMr. Johnson has a total of 30.42 yards of yarn

To Find : Scarfs Mr John will be able to make if he has 30.42 yards of yarn

2.34 yards of yarn = 1 scarf

30.42 yards of yarn = [tex]\frac{30.42}{2.34}[/tex]

                                 = 13 scarfs

Hence , the number of scarfs Mr John will make with 30.42 yards of yarn is 13

How many -pound bags of soap flakes can Mr. Newman fill?

Answers

Answer:

where is the other part of the question

Need more to answer the question.

Could someone use my Gauthmath code 8APGFB to help me gain more tickets? My math review sheet is crazzzzzzy.

Answers

Answer:

Okay

Step-by-step explanation:

I will try to help you

Answer:

Ok I also have a code: F5LS4F

Step-by-step explanation:

I heard you can get tickets in their discord community or something like that.

A closet is is 5 feet wide, 3 feet long, and 6 feet tall. A box with dimensions 2 ft × 3 ft × 2 ft is inside the closet.

How much space in cubic feet is left inside the closet around the box?

Enter your answer in the box.

ft³

Answers

Answer:

78 cm³ of space is left inside the closet.

Step-by-step explanation:

Given that,

A closet is is 5 feet wide, 3 feet long, and 6 feet tall. A box with dimensions 2 ft × 3 ft × 2 ft is inside the closet.

We need to find the space is left inside the closet around the box.

Space left = volume of the closet - volume of the box

= 5×3×6 - 2×3×2

= 90 - 12

= 78 cm³

So, 78 cm³ of space is left inside the closet.

A student made two patterns to show multiplication of a decimal by powers of ten. the equations shown for both patterns are incorrect. pattern A
3.675. 10 =3.7650
3.675. 100= 3.67500
3.675.1,000= 3.675000
pattern B
3.675. 10=3.0675
3.675.0.01= 3.00675
3.675. 0.001= 3.000675
explain why the equations in each of the patterns are false. Include in your explanation the values that should appear on the right side of each equation in both patterns to make the equations true.

Answers

If a student made two patterns to show multiplication of a decimal by powers of ten. All the value are incorrect. The correct value are: 36.75, 367.5, 3,675, 36.75, 0.03675, 0.003675.

How to find the correct value?

Pattern A

3.675×10 =3.7650 Incorrect

3.675×10 = 36.75 Correct

3.675× 100= 3.67500  Incorrect

3.675×100= 367.5 Correct

3.675×1,000= 3.675000 Incorrect

3.675×1,000 = 3,675 Correct

Pattern B

3.675×10=3.0675 Incorrect

3.675× 10= 36.75 Correct

3.675×0.01= 3.00675 Incorrect

3.675×0.01= 0.03675 Correct

3.675×0.001= 3.000675 Incorrect

3.675×0.001= 0.003675 Correct

The correct value are: 36.75, 367.5, 3,675, 36.75, 0.03675, 0.003675.

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Examine the rotation. Which best describes point D?

Answers

We can’t see the rotation
Where is the picture?

8. If 5/12.5 is equivalent to -4/2x, what is the value of x?

Answers

Answer:

-5

Step-by-step explanation:

[tex]\frac{5}{12.5} = \frac{-4}{2x}[/tex]

[tex]5 \cdot 2x = 12.5 \cdot -4[/tex]

[tex]10x = -50[/tex]

[tex]x=-5[/tex]

5. Mariel volunteers at the
animal shelter 3 times a month.
After 6 months, how many
times has she volunteered at
the animal shelter?

Answers

the answer is 18 times

Elise randomly surveyed students at her school to find out their favorite music. the table shows the results if Elise’s survey. if there are 400 students at Elise’s school, how many can she predict will like pop the best?

Answers

Answer:

125 students

Step-by-step explanation:

according to this survey, she surveyed 80 people, and of the 80 people she surveyed, 25 of them said they like pop best

set up a proportion to find how many students will like pop if there are 400 students at her school:

25/80=x/400

80x=10000

x=125

125 students

Can you please help me faster please help me if you know???!!!

Answers

We want the probability of her coffee being large given she ordered a hot drink.
First we find the sum of the customers with hot drinks:
22+5+48=75
The probability of the drink being large given that it’s a hot drink is:
Large hot drinks/sum of hot drinks= 22/75= 0.293333...≈ 29%.

Answer:

29%

Step-by-step explanation:

5+48+22=75

22/75=0.2933

nearest % is 29%



A chef makes small and large snacks to sell at a local art show. He cannot make more than 30
snacks before the show, with no more than 6 large snacks. The chef must make at least 10 small snacks to
earn a profit.
Part A
Let x represent the number of small snacks and y represent the number of large snacks. Given x ≥ 0 and
y 20, select all the inequalities that represent the situation.
0 x≤6
O y ≥ 10
Ox+y≤ 30
O 10x+6y≤ 30
0y≤6
0 x ≥ 10
-01:25

Answers

the inequalities that represent the situation are,

Ox+y≤ 30

0y≤6

0 x ≥ 10

What is inequality?

An inequality is a relation which makes a non-equal comparison between two numbers or mathematical expressions.

Here, given that,

A chef makes small and large snacks to sell at a local art show.

He cannot make more than 30

snacks before the show, with no more than 6 large snacks.

The chef must make at least 10 small snacks to earn a profit.

Let,

x represent the number of small snacks

and y represent the number of large snacks.

Given x ≥ 0 and y 20

So, we get,

the inequalities that represent the situation are,

Ox+y≤ 30

0y≤6

0 x ≥ 10

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lol sorry im being supperrrrrr lazy rn

Answers

I think it’s 7 because 7 x 7 equals 49 which is the area

I need help because I don't understand and I need an explanation of how to do it, please.

Answers

Answer:

Step-by-step explanation:

a.we konw DC=2b and DO=OC, so the coordinate of D(-b, 0), C(b, 0)

b.we konw the height of rectangle is h, so the coordinate of A(-b, h), B(b, h).

5. Find the value of side x and y. Leave answers in simplest radical form a applicable.

Answers

Therefore , as a result, x = 53 and y = 10 are the answers to the trigonometry problem that was presented.

What is trigonometry?

Trigonometry is the discipline of mathematics that studies correlations between angles and sides of triangles. Trigonometry is present in all of geometry because every ahead and move form may indeed be resolved to a set of triangles. Amazingly intricate connections exist between geometry and other areas of mathematics, particularly arithmetic, real or abstract, infinite series, arithmetic, and infinite series.

Here,

Sin 30 = Opposing Side/High

1/2 = 5 / y

y = 5 / (1/2)

y = 10

Cos 30 = Adjustment Side/ Hyp

√3/2 = x/y

√3/2 = x/10

x = 10√3 / 2

x = 5√3

In light of this, the given fractional problem's answer is

x = 5√3 and y = 10.

Therefore , as a result, x = 53 and y = 10 are the answers to the trigonometry problem that was presented.

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Using data from 50 workers, a researcher estimates Wage = β0 + β1Education + β2Experience + β3Age + ε, where Wage is the hourly wage rate and Education, Experience, and Age are the years of higher education, the years of experience, and the age of the worker, respectively. The regression results are shown in the following table.
Coefficients Standard Error t Stat p-Value
Intercept 7.45 3.79 1.97 0.0554
Education 1.06 0.37 2.86 0.0063
Experience 0.37 0.18 2.06 0.0455
Age −0.02 0.06 −0.33 0.7404
Interpret the point estimate for β1.
A. As Education increases by 1 year, Wage is predicted to increase by 1.06/hour.
B. As Education increases by 1 year, Wage is predicted to increase by 0.37/hour.
C. As Education increases by 1 year, Wage is predicted to increase by 1.06/hour, holding Age and Experience constant.
D. As Education increases by 1 year, Wage is predicted to increase by 0.37/hour, holding Age and Experience constant.

Answers

C thank me laterrrrrrrrrrrrrrrrrrr

What is the geometric mean of 12 and 15?

Answers

Answer:

The geometric mean is 9.798

Step-by-step explanation:

Answer:

13.416407864998738

please help it’s due in half an hour

Answers

Answer:

(a) They asked for one value of x

but I'll give you both

They're 2 and -2

(b)g(-1) = 4

Step-by-step explanation:

For (a) they're are looking for the value of x that is corresponding to 1 on the y axis

If you observe from your graph only -2 and 2 will have a corresponding value of 1 therefore they're the answers

for (b) Just look for the corresponding value of -1(x -axis) on the y axis which is 4

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