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2 years ago

Please help! Thankss!! :)

Mathematics

2 answers:

Vsevolod [243]2 years ago

6 0

Answer:

Step-by-step explanation:

If b = -4, then -4(-4) is 16, since 2 negatives is a positive when multiplying or dividing. Then add 16 and 5, since 5 is c. You'll get 21

WITCHER [35]2 years ago

4 0

21
Explanation:
Follow PEMDAS (order of operations) to get answer.
-4(-4)+5
16+5 = 21

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Answer:

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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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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)

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

and the margin of error is given by :

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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:

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