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3 years ago

0=x^2-20 can you solve using square root formula? Then by using quadratic formula?

1 answer:

8 0

Sqrt(x^2) = sqrt(20)

x = +2sqrt(5)
x = -2sqrt(5)

x1 = (- 0 + sqrt(0^2 - 4*1*(-20))) / (2*1)
X2 = (-0 - sqrt(0^2 - 4*1*(-20))) / (2*1)

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What is 67/7 as mixed number

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4 years ago

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard devia

gtnhenbr [62]

Answer:

$n=(\frac{2.58(58.2)}{1})^2 =22546.82 \approx 22547$

So the answer for this case would be n=22547 rounded up to the nearest integer

Step-by-step explanation:

Let's define some notation

$\bar X$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma=58.2$ represent the population standard deviation

n represent the sample size

$ME =1$ represent the margin of error desire

The margin of error is given by this formula:

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

And on this case we have that ME =+1 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

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

The critical value for 99% of confidence interval now can be founded using the normal distribution. The significance would be $\alpha=0.01$ and the critical value $z_{\alpha/2}=2.58$ , replacing into formula (b) we got:

$n=(\frac{2.58(58.2)}{1})^2 =22546.82 \approx 22547$

So the answer for this case would be n=22547 rounded up to the nearest integer

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3 years ago