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lozanna [386]
4 years ago
5

I NEED HELP PLS THIS IS DUE IN 3 HOURS

Mathematics
1 answer:
Mariulka [41]4 years ago
5 0

Answer:

Part 1)  x^{2} -2x-2=(x-1-\sqrt{3})(x-1+\sqrt{3})

Part 2)  x^{2} -6x+4=(x-3-\sqrt{5})(x-3+\sqrt{5})

Step-by-step explanation:

we know that

The formula to solve a quadratic equation of the form

ax^{2} +bx+c=0

is equal to

x=\frac{-b(+/-)\sqrt{b^{2}-4ac}} {2a}

Part 1)

in this problem we have

x^{2} -2x-2=0

so

a=1\\b=-2\\c=-2

substitute in the formula

x=\frac{-(-2)(+/-)\sqrt{-2^{2}-4(1)(-2)}} {2(1)}\\\\x=\frac{2(+/-)\sqrt{12}} {2}\\\\x=\frac{2(+/-)2\sqrt{3}} {2}\\\\x_1=\frac{2(+)2\sqrt{3}} {2}=1+\sqrt{3}\\\\x_2=\frac{2(-)2\sqrt{3}} {2}=1-\sqrt{3}

therefore

x^{2} -2x-2=(x-(1+\sqrt{3}))(x-(1-\sqrt{3}))

x^{2} -2x-2=(x-1-\sqrt{3})(x-1+\sqrt{3})

Part 2)

in this problem we have

x^{2} -6x+4=0

so

a=1\\b=-6\\c=4

substitute in the formula

x=\frac{-(-6)(+/-)\sqrt{-6^{2}-4(1)(4)}} {2(1)}

x=\frac{6(+/-)\sqrt{20}} {2}

x=\frac{6(+/-)2\sqrt{5}} {2}

x_1=\frac{6(+)2\sqrt{5}}{2}=3+\sqrt{5}

x_2=\frac{6(-)2\sqrt{5}}{2}=3-\sqrt{5}

therefore

x^{2} -6x+4=(x-(3+\sqrt{5}))(x-(3-\sqrt{5}))

x^{2} -6x+4=(x-3-\sqrt{5})(x-3+\sqrt{5})

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SSSSS [86.1K]
Given:
n = 20, sample size
xbar = 17.5, sample mean
s = 3.8, sample standard deiation
99% confidence interval

The degrees of freedom is 
df = n-1 = 19

We do not know the population standard deviation, so we should determine t* that corresponds to df = 19.
From a one-tailed distribution, 99% CI means using a p-value of 0.005.
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The 99% confidence interval is
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The 99% confidence interval is
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4 years ago
A survey of 35 individuals who passed the seven exams and obtained the rank of Fellow in the actuarial field finds the average s
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Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

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\bar X=150000 represent the sample mean

\mu population mean (variable of interest)

s=15000 represent the sample standard deviation

n=35 represent the sample size  

Solution to the problem

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

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

In order to calculate the critical value t_{\alpha/2} we need to find first the degrees of freedom, given by:

df=n-1=35-1=34

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: "=-T.INV(0.025,34)".And we see that t_{\alpha/2}=2.032

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150000-2.032\frac{15000}{\sqrt{35}}=144847.94    

150000+2.032\frac{15000}{\sqrt{35}}=155152.06

So on this case the 95% confidence interval would be given by (144847.94;155152.06)    

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