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4 years ago

Answer this one please

Mathematics

1 answer:

Fittoniya [83]4 years ago

4 0

Answer:

105 cm²

Step-by-step explanation:

We can see that the area at the square at the bottom, since one side is 5, is 5²=25. Then, we know that the height of the triangles is 8, the base is 5, and there are 4 of them, so ((5*8)/2)*4=80. Add these up to get 105 as our total

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3x - 4y = 7

Alina [70]

3x - 4y = 7
-(3x + 2y = -5)

= 0 - 6y = 12
-6y = 12
y = -2
The resulting equation would be y = -2.

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3 years ago

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The head librarian at the Library of Congress has asked her assistant for an interval estimate of the mean number of books check

Verdich [7]

Answer:

$n=(\frac{1.960(150)}{90})^2 =10.67 \approx 11$

So the answer for this case would be n=11 rounded up to the nearest integer

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".

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".

$\bar X$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

$\sigma =150$ represent the population standard deviation

n 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)

The confidence interval for this case is given by: (740, 920)

We can find the estimate for the mean and we got:

$\bar X = \frac{740+920}{2} = 830$

and the margin of error is given by :

$ME = \frac{920-740}{2}= 90$

The margin of error is given by this formula:

$ME=z_{\alpha/2}\frac{s}{\sqrt{n}}$ (a)

And on this case we have that ME =90 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=(\frac{z_{\alpha/2} s}{ME})^2$ (b)

The critical value for 95% of confidence interval now can be founded using the normal distribution. And in excel we can use this formla to find it:"=-NORM.INV(0.025;0;1)", and we got $z_{\alpha/2}=1.960$ , replacing into formula (b) we got:

$n=(\frac{1.960(150)}{90})^2 =10.67 \approx 11$

So the answer for this case would be n=11 rounded up to the nearest integer

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3 years ago

What is (½)3. ???????

Karolina [17]

It is hard to tell your precise intention. Choose the appropriate interpretation.

$\frac{1}{2} \times 3 = \frac{1 \times 3}{2} = \frac{3}{2} = 1\frac{1}{2}$

$(\frac{1}{2})^{3} = \frac{1^{3}}{2^{3}} = \frac{1}{8}$

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3 years ago

A triangle has an area of 30 square feet. If the height is four feet less than its base, find the dimensions of the triangle.

NISA [10]

<span>the formula is bh/2=area
b*(b-4)/2=16
(b^2-4b)/2=16
b^2-4b=32
b^2-4b-32=0
(b-8)(b+4)=0

b-8=0
b=8 feet for the base.
h=8-4=4 for the height.
proof
8*4/2=16
32/2=16
16=16</span>

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3 years ago

The length of the house is 50 meters. If 1 km

klasskru [66]

Answer:

5km

Step-by-step explanation:

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