I'm not sure how to do this

Answer:

The half-life of this substance is of 569.27 days.

Step-by-step explanation:

Amount of a substance after t days:

The amount of a substance after t days is given by:

[tex]P(t) = P(0)e^{-kt}[/tex]

In which P(0) is the initial amount and k is the decay rate, as a decimal.

Suppose a sample of a certain substance decayed to 69.4% of its original amount after 300 days.

This means that [tex]P(300) = 0.694P(0)[/tex]. We use this to find k.

[tex]P(t) = P(0)e^{-kt}[/tex]

[tex]0.694 = P(0)e^{-300k}[/tex]

[tex]e^{-300k} = 0.694[/tex]

[tex]\ln{e^{-300k}} = \ln{0.694}[/tex]

[tex]-300k = \ln{0.694}[/tex]

[tex]k = -\frac{\ln{0.694}}{300}[/tex]

[tex]k = 0.0012[/tex]

So

[tex]P(t) = P(0)e^{-0.0012t}[/tex]

What is the half-life (in days) of this substance?

This is t for which P(t) = 0.5P(0). So

[tex]0.5P(0) = P(0)e^{-0.0012t}[/tex]

[tex]e^{-0.0012t} = 0.5[/tex]

[tex]\ln{e^{-0.0012t}} = \ln{0.5}[/tex]

[tex]-0.0012t = \ln{0.5}[/tex]

[tex]t = -\frac{\ln{0.5}}{0.0012}[/tex]

[tex]t = 569.27[/tex]

The half-life of this substance is of 569.27 days.

Answer:

Matthew travels 0.0161 meters per second.

Step-by-step explanation:

Given that Matthew travels 42/50 meters In 26/30 minutes, to find the speed of Mathew in meters per second the following calculation must be performed:

42/50 = 0.84

26/30 = 0.86

0.86 x 60 = 52

0.84 meters in 52 seconds

0.84 / 52 = 0.01615

Therefore, Matthew travels 0.0161 meters per second.

Answer:

{20}, {40}, {20,40}, { }

Answer:

(52.30 ; 52.62)

Step-by-step explanation:

Given :

Sample size, n = 20

Mean, xbar = 52.46

Standard deviation, s = 0.42

We assume a t - distribution

The 90% confidence interval

The confidence interval relation :

C.I = xbar ± Tcritical * s/√n

To obtain the Tcritical value :

Degree of freedom, df = n - 1 ; 20 - 1 = 19 ; α = (1 - 0.90) /2 = 0.1/2 = 0.05

Using the T-distribution table, Tcritical = 1.729

We now have :

C.I = 52.46 ± (1.729 * 0.42/√20)

C. I = 52.46 ± 0.1624

C.I = (52.30 ; 52.62)

-2y=10-5x

-2y/-2=(10-5x)/-2

Y=5/2x-2

Answer:

The volume of water is 396 cubic meter.

Step-by-step explanation:

Area of water, A = 132000 square meter

Height, h = 3 mm = 0.003 m

The volume of water is given by

V = Area x height

V = 132000 x 0.003

V = 396 cubic meter.

Answer: 65 have passport and 30 have passport and voter ID so the remainder of people with voter ID only would be 20

Step-by-step explanation

Answer:

x =5/ (1-a)

Step-by-step explanation:

3x-ax=2x+5​

Subtract 2x from each side

3x -ax-2x = 2x+5-2x

3x -ax -2x = 5

combine like terms

x-ax = 5

Factor out x

x(1-a) =5

Divide each side by 1-a

x =5/ (1-a)

[tex]\boxed{\large{\bold{\textbf{\textsf{{\color{blue}{Answer}}}}}}:)}[/tex]

[tex]3x-ax=2x+5\\\\3x-ax-2x=5\\\\(3-2)x-ax=5\\\\x-ax=5\\\\x(1-a)=5\\\\\dashrightarrow x=\dfrac{5}{1-a}[/tex]

Answer:

first question is D

second question is D .875

Step-by-step explanation:

35*2.5= 87.5

7 divided by 8= .875

Answer:

D   87.5 miles

D  0.875 = 7/8 so it is a decimal that terminates after 3 dp.

Step-by-step explanation:

We write;

Scale Inch x Miles

2.5 x 35 = 87.5 miles

Why??

87.5 miles is found when we use the scale of 35 miles = 1inch

Answer = D 87.5 miles

The second one we can either multiply by 7/8 or divide by 1-7/8 = 1/8 to show that;

1/ 1/8 = 0.125

1-0.125 = 0.875  

Answer:

The point-slope form is y - 2 = 1/2 (x - 3)

Step-by-step explanation:

The point-slope form is y - y1 = m (slope) (x - x1). All I did was plug the numbers in the correct locations to get my answer.

Answer:

5x^2(2-3x)

(n+4)(x+y)

Step-by-step explanation:

9514 1404 393

Answer:

  x = 64°

  y = 26°

Step-by-step explanation:

Angle x and 26° together make a right angle, so ...

  x = 90° -26° = 64°

Angles x and y together make a right angle, so ...

  y = 90° -(90° -26°) = 26°

9514 1404 393

Answer:

  4√x -7

Step-by-step explanation:

Four times the square root of x is written 4√x. Seven less than that is found by subtracting 7:

  [tex]4\sqrt{x}-7[/tex]

Answer:

20%

Step-by-step explanation:

The total number of students is: 4 + 6 + 2 + 2 + 3 + 4 + 6 + 3 = 30 (students)

The probability is: 6/30 = 1/5 = 0.2 = 20%

The probability that the student is a male given that he's a sophomore is approximately 60%.

It is the chance of an event to occur from a total number of outcomes.

The formula for probability is given as:

Probability = Number of required events / Total number of outcomes.

Example:

The probability of getting a head in tossing a coin.

P(H) = 1/2

We have,

The probability that the student is a male given that it's a sophomore can be calculated using the formula:

P(male | sophomore) = P(male and sophomore) / P(sophomore)

The number of male sophomores is 6, and the total number of sophomores is 6+4=10.

So, the probability of selecting a sophomore is:

P(sophomore)

= (number of sophomores) / (total number of students)

= 10 / 23

The number of male sophomores is 6.

So,

The probability of selecting a male sophomore is:

P(male and sophomore) = 6 / 23

Therefore,

The probability that the student is a male given that it's a sophomore is:

P(male | sophomore)

= (6 / 23) / (10 / 23)

= 6 / 10

= 3 / 5

Rounding to the nearest whole percent, we get:

P(male | sophomore) ≈ 60%

Thus,

The probability that the student is a male given that he's a sophomore is approximately 60%.

Learn more about probability here:

https://brainly.com/question/14099682

#SPJ7

Answer:

Step-by-step explanation:

Part A

The x-intercept are the values of the variable "x" for which the value of the function, f(x) is zero (f(x) = 0)

The given parameters are;

The values of the function, f(x) = The company's profit

The values of the independent variable, "x" = The price of erasers

Therefore, at the x-intercept, where the values of the variable "x" are 0 and 8, the profit of the company, (f(x)) is 0 (the company does not make any profit)

2) The maximum value, which is the highest point of the graph with coordinate (4, 270), gives the company's maximum profit, f(x) = $270, and the price of the eraser, x-value, at which the company makes maximum profit which is at the price of an eraser, x = $4

3) The intervals where the function is increasing is 0 ≤ x ≤ 4

At the interval where the function is increasing, the sale price is increasing and the profits are increasing

The intervals where the function is decreasing is 4 ≤ x ≤ 8

At the interval where the function is decreasing, the sale price is increasing and the profits are decreasing

Part B

The appropriate average rate of change of the graph from x = 1 to x = 4 where f(x) = 120 and 270 respectively is given as follows

Rate of change of the graph from x = 1 to x = 4 is (270 -120)/(4 - 1) = 50

The average rate of change of the graph represents that the as the price of the eraser increases by $1.00 the profits increases by $50.00

THIS WAS NOT MY OWN ANSWER, PLEASE LET oeerivona TAKE THE POINTS!!

Following are the responses to the given points:

For point a:

[tex]Diameter\ (d)= 16\ m\\\\[/tex]

Calculating the 3 rotations for every minute:

Calculating time for completing 1 rotation:

[tex]1\ rotation=\frac{60}{3}= 20\ second\\\\period=20 \ second\\\\[/tex]

The standard form of the equation of the sine and cosine function is:

[tex]y=A \sin \{ B(x-c)\} +D\\\\y=A \cos \{ B(x-c)\} +D\\\\[/tex]

Calculating the Amplitue:

[tex]A=\frac{max-min}{2}=\frac{17-1}{2}=\frac{16}{2}=8\\\\Period=\frac{2\pi}{B}\\\\20=\frac{2\pi}{B}\\\\B=\frac{2\pi}{20}\\\\B=\frac{\pi}{10}\\\\[/tex]

Calculating the phase shift:

for [tex]\sin[/tex] function: [tex]c=5[/tex]

for [tex]\cos[/tex] function: [tex]c=10[/tex]

Calculating the vertical shift:

[tex]\to D=\frac{max+ min }{2}=\frac{17+ 1}{2}=\frac{18}{2}=9\\\\y=8 \sin \{ \frac{\pi}{10}(t-5)\} +9\\\\y=8 \cos \{ \frac{\pi}{10}(t-10)\} +9\\\\[/tex]

For point b:

[tex]y> 12\ m\\\\12=8 \sin \{ \frac{\pi}{10}(t-5)\} +9\\\\12-9=8 \sin \{ \frac{\pi}{10}(t-5)\} \\\\3=8 \sin \{ \frac{\pi}{10}(t-5)\} \\\\\frac{3}{8}=\sin \{ \frac{\pi}{10}(t-5)\} \\\\\sin^{-1}\frac{3}{8}=\frac{\pi}{10}(t-5) \\\\\frac{\pi}{10} (0.38439677)=(t-5) \\\\1.22357+5=t \\\\t=6.22357\ second\\\\t=6.22\ second\\\\\sin^{-1}\frac{3}{8}=\frac{\pi}{10}(t-5) \\\\\frac{\pi}{10} (2.7571961)=(t-5) \\\\t=8.7764+5\\\\t=13.78\ second\\\\t_2-t_1=13.7764-6.22357= 7.55283\approx 7.55\ second \\\\[/tex]

Learn more:

Rotation: brainly.in/question/39626227

Answer:

m∠y=41

m∠x=90

Step-by-step explanation:

It is an isosceles triangle, so m∠B=49 too

49+49=98

180-98=82

82÷2=41

m∠y=41

41+49=90

180-90=90

m∠x=90

Answer:

When p=2 , q=-1

3q-2p

3(-1) - 2(2)

(3)-4

-1

When p=-3 , q=4

3(4)-2(-3)

(12 )-(-6)

=18

Answer:

option B

Step-by-step explanation:

option B

gdyfudjfjghfhguftduc

Answer:

The answer is C, no solution.

Step-by-step explanation:

9514 1404 393

Answer:

  726 ft²

Step-by-step explanation:

The perimeter of the room is ...

  P = 2(L+W) = 2(18 +15) = 66 . . . . ft

Then the gross wall area (including windows) is ...

  A = LH = (66 ft)(8 ft) = 528 ft² . . . . gross wall area

The area of the 3 windows is ...

  A = 3×LW = 3×(6 ft)(4 ft) = 72 ft² . . . . window area

The area of the ceiling is ...

  A = LW = (18 ft)(15 ft) = 270 ft² . . . . ceiling area

__

Then the net area to be painted is ...

  gross wall area + ceiling area - window area

  = 528 ft² +270 ft² -72 ft² = 726 ft²

The area that Marta will paint is 726 ft².

Answer:

1)a

the problem asks"what PERCENT of 5 is 4?"

2)part

it gives both the percent and the whole, so your left with the part

3)Whole

4 is a part which is 80%

Step-by-step explanation:

Answer:

(11.847 ; 15.813)

Step-by-step explanation:

We are given 12 samples which are :

8, 20, 20, 11, 18, 12, 6, 5, 7, 22, 12, 25

We use a T-distribution to find the confidence interval since the sample size. is small, n < 30

Using a calculator :

The sample mean, xbar = 13.83

Sample standard deviation, s = 6.87

The confidence interval, C.I

C.I = xbar ± Tcritical * s/√n)

Tcritical at 95%, df = n - 1, 12 - 1 = 11

Tcritical(0.05, 11) = 2.20

Hence,

C.I = 13.83 ± 2.20(6.87/√12)

C.I = 13.83 ± 1.9831981

C. I = (13.83 - 1.983 ; 13.83 + 1.983)

C. I = (11.847 ; 15.813)

Answer:

46.38

Step-by-step explanation:

all the answer are not same but buy calculating its the right answer

Answer:

$11.22

Step-by-step explanation:

100% = 187

1% = 187/100 = $1.87

6% = 1%×6 = 1.87×6 = $11.22

Answer:

In this case, you need to calculate the 6% of the price, which is 187 $.

We only need to multiply the price (187) by the percentage (6%):

187 * 0.06 = 11.22

So the tax would be $11.22

Answer:

Moving upwards with an acceleration.

Step-by-step explanation:

weight of the person  = 195 pounds

Apparent weight = 205 pounds

As the weight increases so the scale is moving upwards with some acceleration.

The scale is in elevator which is moving upwards.

Answer:

Area = 72.62 m²

Step-by-step explanation:

Area of a triangle with the given three sides is given by,

Area = [tex]\sqrt{s(s-a)(s-b)(s-c)}[/tex]

Here, s = [tex]\frac{a+b+c}{2}[/tex]

And a, b, c are the sides of the triangle.

From the question,

a = 20 m, b = 10 m and c = 15 m

s = [tex]\frac{20+10+15}{2}[/tex]

s = 22.5

Substitute these values in the formula,

Area = [tex]\sqrt{22.5(22.5-20)(22.5-10)(22.5-15)}[/tex]

        = [tex]\sqrt{22.5(2.5)(12.5)(7.5)}[/tex]

        = [tex]\sqrt{5273.4375}[/tex]

        = 72.62 m²

Look at one side of the triangle. It forms a right triangle with 45 degree angles.

A 45 degree triangle the base and height are the same, so the height would also be 26.

The hypotenuse(x) of a 45 degree right triangle is the side length time the sqrt(2)

The answer is: 26 sqrt(2)

Answer:

a) Their average weight is of 187 pounds.

b) 0.4562 = 45.62% probability that the maximum safe weight will be exceeded.

c) 0.002 = 0.2% probability that the maximum safe weight will be exceeded

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal Probability Distribution

Problems of normal distributions can be solved using the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

a. If 44 people are on the elevator, and their total weight is 8228 pounds, what is their average weight?

8228/44 = 187

Their average weight is of 187 pounds.

b. If a random sample of 44 adult men ride the elevator, what is the probability that the maximum safe weight will be exceeded?

For men, we have that [tex]\mu = 186, \sigma = 60[/tex]

Sample of 44 means that [tex]n = 44, s = \frac{60}{\sqrt{44}}[/tex]

This probability is 1 subtracted by the p-value of Z when X = 187. So

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

By the Central Limit Theorem

[tex]Z = \frac{X - \mu}{s}[/tex]

[tex]Z = \frac{187 - 186}{\frac{60}{\sqrt{44}}}[/tex]

[tex]Z = 0.11[/tex]

[tex]Z = 0.11[/tex] has a p-value of 0.5438.

1 - 0.5438 = 0.4562

0.4562 = 45.62% probability that the maximum safe weight will be exceeded.

c. If a random sample of 44 adult women ride the elevator, what is the probability that the maximum safe weight will be exceeded?

For women, we have that [tex]\mu = 157, \sigma = 69[/tex]

Sample of 44 means that [tex]n = 44, s = \frac{69}{\sqrt{44}}[/tex]

[tex]Z = \frac{X - \mu}{s}[/tex]

[tex]Z = \frac{187 - 157}{\frac{69}{\sqrt{44}}}[/tex]

[tex]Z = 2.88[/tex]

[tex]Z = 2.88[/tex] has a p-value of 0.998.

1 - 0.998 = 0.002.

0.002 = 0.2% probability that the maximum safe weight will be exceeded

Answer:

x = 5

General Formulas and Concepts:

Pre-Algebra

Equality Properties

Step-by-step explanation:

Step 1: Define

Identify

2(x + 8) = 26

Step 2: Solve for x