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3 years ago

NEED HELP!!!!!!!!!!!!!!!!!!!!!

Mathematics

1 answer:

Aleks [24]3 years ago

5 0

Answer:-602

Step-by-step explanation:

First term=a=-143

common difference=d=-134-(-143)=9

Using the formula

Sn=n/2(2a+d(n-1))

S28=28/2 (2(-143)+9(28-1))

S28=14(-286+9x27)

S28=14(-286+243)

S28=14(-43)

S28=-602

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A standard weight known to weigh 10 grams. Some suspect bias in weights due to manufacturing process. To assess the accuracy of

notsponge [240]

Answer:

a) The 98% confidence interval for the mean weight is between 10.00409 grams and 10.00471 grams

b) 49 measurements are needed.

Step-by-step explanation:

Question a:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.98}{2} = 0.01$

Now, we have to find z in the Ztable as such z has a pvalue of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.01 = 0.99$ , so Z = 2.327.

Now, find the margin of error M as such

$M = z\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

$M = 2.327\frac{0.0003}{\sqrt{5}} = 0.00031$

The lower end of the interval is the sample mean subtracted by M. So it is 10.0044 - 0.00031 = 10.00409 grams

The upper end of the interval is the sample mean added to M. So it is 10 + 0.00031 = 10.00471 grams

The 98% confidence interval for the mean weight is between 10.00409 grams and 10.00471 grams.

(b) How many measurements must be averaged to get a margin of error of +/- 0.0001 with 98% confidence?

We have to find n for which M = 0.0001. So

$M = z\frac{\sigma}{\sqrt{n}}$

$0.0001 = 2.327\frac{0.0003}{\sqrt{n}}$

$0.0001\sqrt{n} = 2.327*0.0003$

$\sqrt{n} = \frac{2.327*0.0003}{0.0001}$

$(\sqrt{n})^2 = (\frac{2.327*0.0003}{0.0001})^2$

$n = 48.73$

Rounding up

49 measurements are needed.

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What is the value of x in the diagram below? 2 right triangles are stacked. The bottom triangle has a side length of 9 units and

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Answer:

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Step-by-step explanation:

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2 years ago

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fomenos

Answer:

y+7=5/4(x-8)

Step-by-step explanation:

y-y1=m(x-x1)

y-(-7)=5/4(x-8)

y+7=5/4(x-8)

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This is the Pythagorean theorem where the 2 legs of a triangle squared add up to equal the squared hypotenuse (a^2 + b^2 = c^2)

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3 years ago

If x varies directly with y and x = 3.5 when y = 14, find x when y = 18.

maks197457 [2]

Answer:

x = 4.5

Step-by-step explanation:

there's definitely other ways to solve this, but I used a proportion.

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Then you can make this equation:

14x = 3.5 * 18

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