Solve for x:

i really need the answer

Solve for x:
i really need the answer

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Ответ:

Jenifermorales101

22.03.2020

Mathematics

a. 0.4333

b. 255

Step-by-step explanation:

The maximum Error E is 1.3

approximately normal test scores,

Standard Deviation, SD is 6.5

a).

Level of confidence = 99.7%

critical value of z for a two tailed test and 0.3% level of significance is 3

since the sample mean is within 0.5 of the true population mean

hence, the standard dev of mean is given by

$Z_{\alpha}[\frac{\sigma}{\sqrt{n}} ]=E$

where E = 1.3

$Z_{\alpha}=$ 1.3

$\frac{\sigma}{\sqrt{n}} =\frac{E}{Z_{\alpha}} \\\\\frac{\sigma}{\sqrt{n}} =\frac{1.3}{3}$

hence the Std of the mean is 0.4333 (to 4 d.p.)

b).

The sample size is computed as follows

making n the subject of formular of the above equation

$\sqrt{n} =\frac{3\sigma}{1.3}} \\\\\sqrt{n} =\frac{3\times 6.5}{1.3}} \\\\n=(\frac{3\times 6.5}{1.3}})^2$

hence,

n = 255

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