A random sample of 64 items is selected from a population of 400 items. The sample mean is 200. The population standard deviation is 48. From this data, a 95% confidence interval to estimate the population mean can be computed as

Respuesta :

Answer:   [tex](188.24,\ 211.76 )[/tex].

Step-by-step explanation:

Given : Sample size : n= 64 , the sample is a large sample (n>30), so we can apply z-test.

Sample mean = [tex]\overline{x}=200[/tex]

Standard deviation : [tex]\sigma=48[/tex]

Level of confidence:[tex]1-\alpha=0.95[/tex]

[tex]\Rightarrow\ \alpha=0.05[/tex]

Then, critical z-value =[tex]z_{\alpha/2}=1.96[/tex]

The  confidence interval to estimate the population mean is given by :_

[tex]\overline{x}\ \pm\ z_{\alpha/2}\dfrac{\sigma}{\sqrt{n}}[/tex]

[tex]=200\ \pm\ (1.96)\dfrac{48}{\sqrt{64}}\\\\=200\pm11.76=(200-11.76, 200+11.76)=(188.24,\ 211.76 )[/tex]

Hence, the  95% confidence interval to estimate the population mean can be computed as [tex](188.24,\ 211.76 )[/tex].

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