Find solutions to the linear equation y=−10x+30.

How many ways can 10 runners finish first, second, and third in a race?

olga nikolaevna [1]

Let's call the 10 runners A B C D E F G H I J
ABC
ABD
ABE
ABF
ABG
ABH
ABI
ABJ
ACB
ACD
ACE
ACF
ACG
ACH
ACI
ACJ
ADB
ADC
ADE
ADF
ADG
ADH
ADI
ADJ
AEB
AEC
AED
AEF
AEG
AEH
AEI
AEJ
AFB
AFC
AFD
AFE
AFG
AFH
AFI
AFJ
AGB
AGC
AGD
AGE
AGF
AGH
AGI
AGJ
AHB
AHC
AHD
AHE
AHF
AHG
AHI
AHJ
AIB
AIC
AID
AIE
AIF
AIG
AIH
AIJ
AJB
AJC
AJD
AJE
AJF
AJG
AJH
AJI
The above is 60 different ways, but now B C D E F G H I J have to come first, and the proses starts again, until we have covered them all. I'm not going to write them all out but in theory, there is 540 different ways. 9*60=540.

4 0

3 years ago

Calculate two iterations of Newton's Method to approximate a zero of the function using the given initial guess. (Round your ans

VikaD [51]

Answer:

The two iterations of f(x) = 1.5598

Step-by-step explanation:

If we apply Newton's iterations method, we get a new guess of a zero of a function, f(x), xₙ₊₁, using a previous guess of, xₙ.

xₙ₊₁ = xₙ - f(xₙ) / f'(xₙ)

Given;

f(xₙ) = cos x, then f'(xₙ) = - sin x

cos x / - sin x = -cot x

substitute in "-cot x" into the equation

xₙ₊₁ = xₙ - (- cot x)

xₙ₊₁ = xₙ + cot x

x₁ = 0.7

first iteration

x₂ = 0.7 + cot (0.7)

x₂ = 0.7 + 1.18724

x₂ = 1.88724

second iteration

x₃ = 1.88724 + cot (1.88724)

x₃ = 1.88724 - 0.32744

x₃ = 1.5598

To four decimal places = 1.5598

4 0

2 years ago

O is the centre of the circle, EF is a tangent, angle BCE=28 degrees, angle ACD=31 degrees.

Yuki888 [10]

Answer:

a. 28˚

b. 76˚

c. 104˚

d. 56˚

Step-by-step explanation

a. because angle between tangent and chord is equal to the angle(s) in alternate segment.

b. because angles in triangles add up to 180˚, 180-28=152 and because isosceles triangle, 152/2=76˚

c. because angles in triangles add up to 180˚ and opposite angles in a cyclic quadrilateral add up to 180˚, 31+76=107, 180-107=73, 73-28=45, angles in triangle so 180-(31+45)=104˚

d. 28*2=56˚ because angles at circumference are half angles at centre

4 0

2 years ago

Consider the computer output below. Fill in the missing information. Round your answers to two decimal places (e.g. 98.76). Test

slamgirl [31]

Answer:

$SE_{Mean}=\frac{s}{\sqrt{n}}=\frac{4.77}{\sqrt{19}}=1.094$

$t=\frac{98.77-100}{\frac{4.77}{\sqrt{19}}}=-1.124$

The 95% confidence interval would be given by (96.625;100.915)

a) $df=n-1= 19-1= 18$

b) $p_v =2*P(t_{18}$

If we compare the p value and a significance level for example $\alpha=0.05$ we see that $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis.

c) The only thing that changes is the p value and would be given by:

$p_v =P(t_{18}>-1.124)=0.862$

But again since the p value is higher than the significance level we fail to reject the null hypothesis.

Step-by-step explanation:

Previous concepts and data given

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The central limit theorem states that "if we have a population with mean μ and standard deviation σ and take sufficiently large random samples from the population with replacement, then the distribution of the sample means will be approximately normally distributed. This will hold true regardless of whether the source population is normal or skewed, provided the sample size is sufficiently large".

$\bar X=98.77$ represent the sample mean

$s=4.77$ represent the sample standard deviation

n=19 represent the sample selected

$\alpha$ significance level

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if we have significant difference on the mean of 100, the system of hypothesis would be:

Null hypothesis: $\mu = 100$

Alternative hypothesis: $\mu \neq 100$

From the central limit theorem we know that the distribution for the sample mean $\bar X$ is given by:

$\bar X \sim N(\mu, \frac{\sigma}{\sqrt{n}})$

And we can calculate the Standard error for the mean like this:

$SE_{Mean}=\frac{s}{\sqrt{n}}=\frac{4.77}{\sqrt{19}}=1.094$

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

Since the Confidence is 0.95 or 95%, the value of $\alpha=0.05$ and $\alpha/2 =0.025$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.025,0,1)".And we see that $z_{\alpha/2}=1.96$

Now we have everything in order to replace into formula (1):

$98.77-1.96\frac{4.77}{\sqrt{19}}=96.625$

$98.77+1.96\frac{4.77}{\sqrt{19}}=100.915$

So on this case the 95% confidence interval would be given by (96.625;100.915)

Part a

The degree of freedom are given by:

$df=n-1= 19-1= 18$

Part b

If we analyze the size for the sample is < 30 and we don't know the population deviation so is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}$ (1)

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

We can replace in formula (1) the info given like this:

$t=\frac{98.77-100}{\frac{4.77}{\sqrt{19}}}=-1.124$

Then since is a two sided test the p value would be:

$p_v =2*P(t_{18}$

If we compare the p value and a significance level for example $\alpha=0.05$ we see that $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis.

Part c

If the system of hypothesis on this case are:

Null hypothesis: $\mu = 100$

Alternative hypothesis: $\mu > 100$

The only thing that changes is the p value and would be given by:

$p_v =P(t_{18}>-1.124)=0.862$

But again since the p value is higher than the significance level we fail to reject the null hypothesis.

7 0

2 years ago

Which of the following show the factored equivalent of f(x) = (x2 - 81)(x + 5) and its zeroes. f(x) = (x - 6)(x + 6)(x + 5); x=

andrezito [222]

The correct answer is: [B]:
________________________________________________________
<span> f(x) = (x - 9)(x + 9)(x + 5); x= 9, -9, -5 .
________________________________________________________

</span>

8 0

2 years ago

Read 2 more answers