Answer:
17
Step-by-step explanation:
At a time denoted as t=0, a student carrying a new flu virus comes back to an isolated campus that has a fixed number of 1000 people. Determine a differential equation for the number of people x(t) who have contracted the flu if the rate at which the disease spreads is proportional to the number of interactions between the people who have the flu and the number of people who have not yet been exposed to it. (Please use k as the proportional constant.)
Answer:
[tex]\dfrac{dx(t)}{dt} = kx(t)[1000-x(t)],$ x(0)=0[/tex]
Step-by-step explanation:
Total Number of People on Campus =1000
Let the number of people who have contracted the flu =x(t)
Therefore, the number of people who have not contracted the flu =1000-x(t)
Since the rate at which the disease spreads is proportional to the number of interactions between the people who have the flu and the number of people who have not yet been exposed to it.
[tex]\dfrac{dx(t)}{dt} \propto x(t)[1000-x(t)][/tex]
Introducing the proportional constant k, we obtain:
[tex]\dfrac{dx(t)}{dt} = kx(t)[1000-x(t)][/tex]
At t=0, there was no infected on the campus, therefore the initial condition is given:
[tex]x(0)=0[/tex]
Therefore, a differential equation for the number of people x(t) who have contracted the flu is:
[tex]\dfrac{dx(t)}{dt} = kx(t)[1000-x(t)],$ x(0)=0[/tex]
A group of scientists wants to investigate if they can predict the life expectancy
Step-by-step explanation:
There is no question asked here, bit of course it is possible to predict the life expectancies of a lot of things. This takes patience, resistance, and persistence, because working on something that takes time without persistence would result in a painful waste of time.
To predict the life expectancy of an effect is to predict how long it is going to take before it goes extinct, or seize from existence.
Is this right ? Anyone ?
Answer:
yes this right, it depends on what one tho
Step-by-step explanation:
Select the correct answer.
What is 22% of 50?
OA.
44
OB.
28
Oc.
22
OD.
11
Answer:
11
Step-by-step explanation:
¿Pueden ser complementarios un ángulo agudo y un ángulo obtuso?
Answer:
No porque si sumas los dos el resultado es más de 90 grados.
Step-by-step explanation:
An economist wants to test if there is any difference in income between Escambia county and Miami-Dade county in Florida. To do this, she collects random samples of residents from both these counties. The information collected from these samples is tabulated below. Assume that both the populations are normally distributed with equal population variances.
Escambia County (Population 1) Miami-Dade County (Population 2)
n 1 = 11 n 2 = 15
x ¯ 1 = 36,700 x ¯ 2 = 34 ,700
s 1 = 7800 s 2 = 7375
Set up the null and alternative hypotheses to test the economist’s claim.
a) H_0 : μ1- μ2 is less than or equal to 0 versus H_a: is μ1- μ2 greater than 0b) H_0 : μ1 <μ2 versus H_a: is μ1 is greater than or equal to μ2c) H_0 : μ1 is not equal to μ2 versus H_a: is μ1 is equal to μ2d) H_0 : μ1- μ2 is greater than or equal to 0 versus H_a: is μ1- μ2 is less than 0e) H_0 : μ1- μ2 = 0 versus H_a: is μ1- μ2 not equal t0 0
Answer:
Yo
Step-by-step explanation:
[Pic] Find the volume of the pyramid.
Answer:
Step-by-step explanation:
Darío buys applesauce cups for a family reunion. He needs 23 cups, and he buys them in packs of 6. How many packs does Dario need?
Answer:
He needs four packs.
Step-by-step explanation:
6*4=24 there is 23 so he will need 4 packs in total.
Answer:
4 packs
Step-by-step explanation:
3 packs only gives him 18 and he needs atleast 23. The closest number that meets 23 is 24. It takes 4 packs of 6 to get 24.
Suppose an actual census showed that 20% of the households in Michigan have incomes in excess of $60,000. Assume that a random sample of 500 households in Michigan is taken. Then, the standard error of the sampling distribution of sample proportion of households who have incomes in excess of $60,000 will be:
Answer: 0.0179
Step-by-step explanation:
We know that , the standard error of the sampling distribution of sample proportion (p) is given by :-
[tex]S.E.=\sqrt{\dfrac{p(1-p)}{n}}[/tex]
where , n= sample size
Let p be the proportion of households who have incomes in excess of $60,000 .
As per given , we have
p= 20% = 0.20
n= 500
Then,
[tex]S.E.=\sqrt{\dfrac{0.20(1-0.20)}{500}}=\sqrt{\dfrac{0.20\times0.80}{500}}\\\\=\sqrt{0.00032}\\\\=0.01788854382\approx0.0179[/tex]
Hence, the standard error of the sampling distribution of sample proportion of households who have incomes in excess of $60,000 is 0.0179.
The standard error of the sampling distribution of sample proportion of households who have incomes in excess of $60,000 will be 0.0179.
Calculation of the standard error:Since an actual census showed that 20% of the households in Michigan have incomes in excess of $60,000.
So here the standard error should be
[tex]\sqrt (.2\times (1-.2)\div 500) \\\\= 0.0179[/tex]
Hence, the standard error should be 0.0179.
Learn more about sample here: https://brainly.com/question/9222927
If f(x) = 2x2 - 5 and g(x) = 3x + 3, find (f - g)(x).
A. 3x – 2x2 - 2
B. 2x2 – 3x - 2
C. 2x2 – 3x-8
D. - x² – 8
Answer:
2x^2 -3x -8
Step-by-step explanation:
f(x) = 2x^2 - 5
g(x) = 3x + 3,
(f - g)(x)= 2x^2 - 5 -(3x + 3)
Distribute the minus sign
(f - g)(x)= 2x^2 - 5 -3x - 3
Combine like terms
= 2x^2 -3x -8
write the equation of a line that is perpendicular to the given line and that passes through the given point. -3x - 6y = 17; (6, 3)
Answer:
Y=2x-9
Step-by-step explanation:
Please answer this correctly
Answer:
3.00
Step-by-step explanation:
3.14 is rounded to 3.00
Answer:
141.3 m²
Step-by-step explanation:
V= πr²h
V=3.14*(6/2)²*5= 141.3 m²
Ashley and Robbin bought identical backpacks at different stores. Ashley’s backpack originally cost $65 and was discounted 25%. Robbin’s backpack originally cost $75 and was on sale for 30% off of the original price. Which backpack is the better buy? Explain.
Answer:
Ashley’s backpack is the better buy.
Step-by-step explanation:
You have to calculate the price that was paid for each backpack after the discount was applied.
Ashley’s backpack: $65*0.25= $16.25
Final price= $65-$16.25= $48.75
Robbin's backpack: $75*0.3= $22.5
Final price= $75-$22.5= $52.5
According to this, the backpack that is the better buy is the one that Ashley bought because after the discounts were applied it cost $48.75 and Robbin's backpack cost $52.2 which means that Ashley's backpack was cheaper.
Find the indicated probability. The weekly salaries of teachers in one state are normally distributed with a mean of $490 and a standard deviation of $45. What is the probability that a randomly selected teacher earns more than $525 a week
Given Information:
Mean weekly salary = μ = $490
Standard deviation of weekly salary = σ = $45
Required Information:
P(X > $525) = ?
Answer:
P(X > $525) = 21.77%
Step-by-step explanation:
We want to find out the probability that a randomly selected teacher earns more than $525 a week.
[tex]P(X > 525) = 1 - P(X < 525)\\\\P(X > 525) = 1 - P(Z < \frac{x - \mu}{\sigma} )\\\\P(X > 525) = 1 - P(Z < \frac{525 - 490}{45} )\\\\P(X > 525) = 1 - P(Z < \frac{35}{45} )\\\\P(X > 525) = 1 - P(Z < 0.78)\\\\[/tex]
The z-score corresponding to 0.78 from the z-table is 0.7823
[tex]P(X > 525) = 1 - 0.7823\\\\P(X > 525) = 0.2177\\\\P(X > 525) = 21.77 \%[/tex]
Therefore, there is 21.77% probability that a randomly selected teacher earns more than $525 a week.
How to use z-table?
Step 1:
In the z-table, find the two-digit number on the left side corresponding to your z-score. (e.g 0.7, 2.2, 1.5 etc.)
Step 2:
Then look up at the top of z-table to find the remaining decimal point in the range of 0.00 to 0.09. (e.g. if you are looking for 0.78 then go for 0.08 column)
Step 3:
Finally, find the corresponding probability from the z-table at the intersection of step 1 and step 2.
What general conclusions can be drawn when you compare salaries with education levels?
Answer:
typically, careers that require higher education levels pay higher salaries than those that require a high school diploma.
A recent study reported that 73% of Americans could only converse in one language. A random sample of 130 Americans was randomly selected. What is the probability that 100 or fewer of these Americans could only converse in one language?
Answer:
Probability that 100 or fewer of these Americans could only converse in one language is 0.8599.
Step-by-step explanation:
We are given that a recent study reported that 73% of Americans could only converse in one language.
A random sample of 130 Americans was randomly selected.
Let [tex]\hat p[/tex] = sample proportion of Americans who could only converse in one language.
The z score probability distribution for sample proportion is given by;
Z = [tex]\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] ~ N(0,1)
where, p = population proportion of Americans who could only converse in one language = 73%
[tex]\hat p[/tex] = sample proportion = [tex]\frac{100}{130}[/tex] = 0.77
n = sample of Americans = 130
Now, probability that 100 or fewer of these Americans could only converse in one language is given by = P( [tex]\hat p[/tex] [tex]\leq[/tex] 0.77)
P( [tex]\hat p[/tex] [tex]\leq[/tex] 0.77) = P( [tex]\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] [tex]\leq[/tex] [tex]\frac{0.77-0.73}{\sqrt{\frac{0.77(1-0.77)}{130} } }[/tex] ) = P(Z [tex]\leq[/tex] 1.08) = 0.8599
The above probability is calculated by looking at the value of x = 1.08 in the z table which has an area of 0.8599.
There is a 0.9986 probability that a randomly selected 30 year old male lives through the year (based on data from the US department of Health and Human Services). A Fidelity life insurance company charges $161 for insuring that the male will live through the year. If the male does not survive the year, the policy pays out $100,000 as a death benefit. If a 30 year old male purchases the policy, what is his expected value?
Answer:
a) Surviving the year: $ -161. Not surviving: 99,839.
b) 0.9986 * -161 + (1-0.9986) * 100000 = -20.7746
c) As the expected value is negative from the male's perspective, it is positive from the insurance company's perspective. So as the number of people purchasing this insurance becomes large, the company's profit will converge to an average value of 20.7746 per male. So the company is indeed profitting.
Which operation should you perform last in the expression 32 + 2?
Answer:
Step-by-step explanation:
Adding the numbers because that is the only step. Making it the last operation.
A professor notices that more and more students are using their notebook computers in class, presumably to take notes. He wonders if this may actually improve academic success. To test this, the professor records the number of times each student uses his or her computer during a class for one semester and the final grade in the class (out of 100 points). If notebook computer use during class is related to improved academic success, then a positive correlation should be evident. Given the following data, test whether notebook computer use and grades are related at a .05 level of significance.
State the conclusions for this test using APA format. First, describe the correlation coefficient in words and give the value of r. Then give the value of R2 and describe (in words) the effect size using the coefficient of determination. Finally, is there a significant relationship?
Answer:
Step-by-step explanation:
The hypothesis being tested is:
H0: ρ = 0
Ha: ρ ≠ 0
Pearson's r is -0.140.
The critical r-value is 0.404.
Since 0.140 < 0.404, we cannot reject the null hypothesis.
Therefore, we cannot conclude that notebook computer use and grades are related.
Pearson's r is -0.140. It means that there is a weak negative relationship between notebook computer use and grades.
The coefficient of determination is 0.020. 2% of the variation in the model is explained.
The relationship is not significant.
Notebook Computer Use Final Grade for Course
30 86
23 88
6 94
0 56
24 78
36 72
10 80
0 90
0 82
8 60
12 84
18 74
0 78
32 66
36 54
12 98
8 81
18 74
22 70
38 90
5 85
29 93
26 67
10 80
r² = 0.020
r = -0.140
Std. Error = 11.996
n = 24
k = 1
ANOVA table
Source SS df MS F p-value
Regression 63.6652 1 63.6652 0.44 0.5129
Residual 3,165.668 22 143.8940
Total 3,229.333 23
A notebook costs £1.30, a pen costs 38p , a pencil costs 21p and a sharpener costs 84p.
Remi buys 2 pencils, 3 pens, 2 sharpeners and some notebooks.
He pays with £10 and receives 26p change.
How many notebooks did he buy?
Answer:5
Step-by-step explanation:
Please help I will mark you a brainliest
Answer:
[tex]sin\;60 =\frac{\sqrt{3} }{2}[/tex]
A = 4 0 0 1 3 0 −2 3 −1 Find the characteristic polynomial for the matrix A. (Write your answer in terms of λ.) Find the real eigenvalues for the matrix A. (Enter your answers as a comma-separated list.) λ = Find a basis for each eigenspace for the matrix A.
Answer:
Step-by-step explanation:
We are given the matrix
[tex] A = \left[\begin{matrix}4&0&0 \\ 1&3&0 \\-2&3&-1 \end{matrix}\right] [/tex]
a) To find the characteristic polynomial we calculate [tex]\text{det}(A-\lambda I)=0[/tex] where I is the identity matrix of appropiate size. in this case the characteristic polynomial is
[tex]\left|\begin{matrix}4-\lambda&0&0 \\ 1&3-\lambda&0 \\-2&3&-1-\lambda \end{matrix}\right|=0[/tex]
Since this matrix is upper triangular, its determinant is the multiplication of the diagonal entries, that is
[tex](4-\lambda)(3-\lambda)(-1-\lambda)=(\lambda-4)(\lambda-3)(\lambda+1)=0[/tex]
which is the characteristic polynomial of A.
b) To find the eigenvalues of A, we find the roots of the characteristic polynomials. In this case they are [tex]\lambda=4,3,-1[/tex]
c) To find the base associated to the eigenvalue lambda, we replace the value of lambda in the expression [tex]A-\lambda I[/tex] and solve the system [tex](A-\lambda I)x =0[/tex] by finding a base for its solution space. We will show this process for one value of lambda and give the solution for the other cases.
Consider [tex]\lambda = 4[/tex]. We get the matrix
[tex]\left[\begin{matrix}0&0&0 \\ 1&-1&0 \\-2&3&-5 \end{matrix}\right] [/tex]
The second line gives us the equation x-y =0. Which implies that x=y. The third line gives us the equation -2x+3y-5z=0. Since x=y, it becomes y-5z =0. This implies that y = 5z. So, combining this equations, the solution of the homogeneus system is given by
[tex](x,y,z) = (5z,5z,z) = z(5,5,1)[/tex]
So, the base for this eigenspace is the vector (5,5,1).
If [tex]\lambda = 3[/tex] then the base is (0,4,3) and if [tex]\lambda = -1[/tex] then the base is (0,0,1)
An analogy: For this set of questions, choose between two cars that we will call "A" and "B." Car A is a two-door coupe. It gets 60 miles per gallon and has a 10-gallon tank. Car B is an SUV. It gets 2 miles per gallon and has a 60-gallon tank. Suppose both cars embark on a very long journey together, side by side, each with a full tank of gas. Which car holds more fuel?
Car B, the SUV, obviously holds more fuel after 0 driven miles, 60 gallons, while car A holds 10 gallons after 0 miles.
let's speak about miles with the abbreviation x.
sk at x=0 Car B got more fuel.
Car A gets 60 Miles per gallon, it's consuming 1/60 gallon per mile. The amount of fuel decreases by 1/60 per mile
After each mile, or each x-step, Car A has
This can be expressed mathematically:
A(x) = -1/60*x + 10
The -1/60x is, again, the consumption per mile, the +10 is the full tank at the start.
A(0)= -1/60*0 + 10
=10
For Car B the consumption is 1/2 gallons per mile and the tank holds 60 gallons of fuel, wich ammount is decreases with traveled distance.
B(x) = -1/2*x + 60
See that we could draw these two functions as lines in a coordinate system. (I did it with desmos btw). This step is just to help understand.
After some distance/ amount x of miles, Car A will hold more fuel than car B, because it drives more efficiently.
In the picture we can see that this is after about 100 miles and we could guess the amount of fuel, but I won't. Let's calculate it and then answer the question precisely.
We get the intersection of the two lines by setting them equal, a(x)=b(x)
-1/60x + 10 = -1/2x + 60
Exactly one point lies, equally, on both lines
So let's solve for x
Further on the right, each step is explained. we have to do the same operation on both sides of the equation, just to not break it.
-1/60x + 10 = -1/2x + 60 | -10
-1/60x = -1/2x + 50 | + 1/2x
-1/60x + 1/2x = 50 | *60
-1x + 30x = 3000
29x = 3000 | /29
x = 103.448275862
so after about 103.45 miles, Car B holds less fuel than Car A (and Car A more than Car B), until both are empty. Car B could therefore drive more miles
We can also ask how much fuel is left in both tanks at the intersection point by plugging the x-value we got into one of the equations (doesn't matter which one, since the point is the same)
a(103.4482) = -1/60 * 103.4482 + 10 = 8.28
If you want it to be precise, stay with fractions
a(3000/29) = -1/60 * 3000/29 + 10
= -50/29 +10
= 9 -21/29
= 8 + 8/29
Finding out how far each car could travel would be achieved by setting their fuel-equation equal to 0, because that's the value of it when they run of of fuel. For example 0 = -1/60x+10, then you (just) solve for x.
I did overshoot the given problem to offer offer you understanding that's spans more of the topic you are dealing with
(would really appreciate the brainliest)
A box has a volume of 22 1/2 in³. Find the length of the box!
Answer:
Length = 2.823 in (to 3 decimal places)
Step-by-step explanation:
assuming that the box is a cubic box:
volume of box = [tex]22\frac{1}{2}[/tex] in³ = 22.5 in³
volume = Length × Length × Length = (Length)³
∴ (Length)³ = 22.5
∴ Length = ∛(22.5)
using the calculator punch ∛(22.5), and the answer is:
∴ Length = 2.823 in (to 3 decimal places)
A park in the shape of quadrilateral PQRS is bordered by four sidewalks. Find the measure of each
exterior angle of the park.
15z=
7z=
7z=
11z=
Answer:
135°, 63°, 63°, 99°
Step-by-step explanation:
Find attached the diagram used in solving the question.
We would use formula for sum of interior angles to get each exterior angle.
From the diagram, we added additional variables to be able to solve for sum of interior angles.
Sum of angle on a straight line = 180°
a° +15z° = 180°
b° +7z° = 180°
c° +7z° = 180°
d° +11z° = 180°
Where a,b,c and d are interior angles
Sum of interior angles = 180(n-2)
n = number of sides
For quadrilateral, n= 4
a°+b°+c°+d° = 180(n-2)
180-15z +180-7z+180-7z+180-11z = 180(4-2)
720-40z = 180(2)
720 - 360 = 40z
z = 360/40
z = 9
Each exterior angle:
15z = 15×9 = 135°
7z = 7×9 = 63°
7z = 7×9 = 63°
11z = 11×9 = 99°
Ajar contains 12 red balls, 7 green balls, 10 white balls, and 7 yellow balls.
Two balls are chosen from the jar, with replacement. What is the
probability that both balls chosen are green? Is this a dependent or
independent event? *
A. Independent, 1/30
B. Dependent, 1/30
C. Independent, 49/1296
D. Dependent, 49/1296
Answer:
C. Independent, 49/1296
Step-by-step explanation:
A jar contains 12 red balls, 7 green balls, 10 white balls, and 7 yellow balls.
Total balls = 12+7+10+7
Total balls= 36
Two balls are chosen at random with replacement.
The probability that the both balls are green = probability of the first ball to he green * probability of the second ball to be green
The probability that the both balls are green= 7/36 * 7/36
The probability that the both balls are green= 49/1296
The probability that the both balls are green= 49/1296
A test was made of H0: μ1 = μ2 versus H1: μ1 < μ2. The sample means were and the sample standard deviations were and and the sample sizes were and Is H0 rejected at the 0.05 level? (Hint: First compute the value of the test statistic.)
Answer:
Step-by-step explanation:
Hello!
Hypotheses:
H₀: μ₁ = μ₂
H₁: μ₁ < μ₂
α: 0.05
Using the following sample information:
Sample 1
n₁= 15
X[bar]₁= 10
S₁= 4
Sample 2
n₂= 27
X[bar]₂= 8
S₂= 7
This is an example of a t-test for independent samples, assuming both unknown populations variances are equal the statistic is:
[tex]t= \frac{(X[bar]_1-X[bar]_2)-(Mu_1-Mu_2)}{Sa*\sqrt{\frac{1}{n_1} +\frac{1}{n_2} } } ~~t_{n_1+n_2-2}[/tex]
[tex]Sa= \sqrt{\frac{(n_1-1)S^2_1+(n_2-1)S^2_2}{n_1+n_2-2} } = \sqrt{\frac{14*16+26*49}{15+27-2} }= \sqrt{\frac{1498}{40} } = 6.119= 6.12[/tex]
[tex]t= \frac{(10-8)-0}{6.12*\sqrt{\frac{1}{15} +\frac{1}{27} } }= 1.01[/tex]
The p-value of this test is 0.1593
To decide using the p-value approach you have to use the following rule:
If p-value ≤ α, reject the null hypothesis.
If p-value > α, do not reject the null hypothesis.
The calculated p-value is greater than the significance level, the decision is to not reject the null hypothesis.
Using a 5% significance level you can conclude that the hypothesis test is not significant and the population means of populations 1 and 2 are equal.
I hope this helps!
Which expression is equal to 5y^3÷5y^-2
Answer:
[tex]5y^3/5y^-2[/tex] = [tex]y^5[/tex]
Step-by-step explanation:
[tex]5y^3/5y^-2[/tex]
as 5 is both in numerator and denominator it will get cancelled so we have now expression
[tex]y^3/y^-2[/tex]
we will use law of indices wherein if there is
[tex]a^x/a^y = a^(x-y)[/tex]
which means that if the base is same in numerator and denominator then we have to subtract the power of denominator from numerator to get the reduced form using this concept
here power in numerator is 3 and power in denominator is -2
hence we will be subtracting -2 from 3
[tex]y^3/y^-2 = y^(3-(-2) = y^(3+2) = y^5[/tex]
Thus,
[tex]5y^3/5y^-2[/tex] = [tex]y^5[/tex]
The National Center for Educational Statistics surveyed 5400 college graduates about the lengths of time required to earn their bachelors degrees. The mean is 5.4 years and the standard deviation is 1.9 years. Based on this sample, construct a 90% confidence interval for the mean time required by all college graduates
Answer:
The 90% confidence interval for the mean time required by all college graduates is between 5.36 years and 5.44 years.
Step-by-step explanation:
We have that to find our [tex]\alpha[/tex] level, that is the subtraction of 1 by the confidence interval divided by 2. So:
[tex]\alpha = \frac{1-0.9}{2} = 0.05[/tex]
Now, we have to find z in the Ztable as such z has a pvalue of [tex]1-\alpha[/tex].
So it is z with a pvalue of [tex]1-0.05 = 0.95[/tex], so [tex]z = 1.645[/tex]
Now, find the margin of error M as such
[tex]M = z*\frac{\sigma}{\sqrt{n}}[/tex]
In which [tex]\sigma[/tex] is the standard deviation of the population and n is the size of the sample.
[tex]M = 1.645*\frac{1.9}{\sqrt{4500}} = 0.04[/tex]
The lower end of the interval is the sample mean subtracted by M. So it is 5.4 - 0.04 = 5.36 years.
The upper end of the interval is the sample mean added to M. So it is 5.4 + 0.04 = 5.44 years.
The 90% confidence interval for the mean time required by all college graduates is between 5.36 years and 5.44 years.
A random sample of 100 college students is taken from the student body of a large university Assume that, in fact, a population mean of 20 hours and a standard deviation of 15 hours describe the weekly study estimates for the entire student body. Therefore, the sampling distribution of the mean has a mean that:________.
a) approximates 20 hours.
b) equals 20 hours.
c) lies within a couple of hours of 20.
d) equals the one observed sample mean.
Answer:
b) equals 20 hours.
Step-by-step explanation:
The sampling distribution of means refers to the distribution of all the possible sample means, with a certain sample size (in this case, n=100) extracted from the population.
The sampling distribution of the means is equal to the population mean. That does not mean that every sample will result in a mean equal to the population, but that the population of sample means will have an average of 20 hours.
