The diameters of aluminum alloy rods produced on an extrusion machine are known to have a standard deviation of 0.0001 in. A random sample of 25 rods has an average diameter of 0.5046 in.1)Test the hypothesis that mean rod diameter is0.5025 in. Assume a two-sided alternative and use α=0.05.2)Find the P-value for this test. 3)Construct a 95% two-sided confidence interval on the mean rod diameter.

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Answer:

The null hypothesis is rejected this means that [tex]\mu \ne 0.5025[/tex]

The 95% confidence interval is [tex]0.5045608 < \mu < 0.5046392 [/tex]

Step-by-step explanation:

From the question we are told that

The standard deviation is s= 0.0001

The sample size is n = 25

The sample mean is [tex]\= x = 0.5046 \ in[/tex]

The population mean is [tex]\mu = 0.5025 \ in[/tex]

The null hypothesis is [tex]H_o : \mu = 0.5025[/tex]

The alternative hypothesis is [tex]H_a : \mu \ne 0.5025[/tex]

The test statistics is mathematically represented as

[tex]t = \frac{0.5046 - 0.5025}{ \frac{0.0001}{\sqrt{25} } }[/tex]

[tex]t = 105[/tex]

So the p-value from the z-table is mathematically represented as

[tex]p-value = 2 * P( z > 105)[/tex]

[tex]p-value = 0.000[/tex]

seeing that

[tex]p-value < \alpha[/tex] we reject the null hypothesis

The critical value of

[tex]\frac{\alpha }{2}[/tex] obtained from the normal distribution table is

[tex]Z_{\frac{\alpha }{2} } = 1.96[/tex]

The margin of error is mathematically represented as

[tex]E = Z_{\frac{\alpha }{2} }*\frac{s}{\sqrt{n} }[/tex]

=> [tex]E = 1.96 *\frac{0.0001}{\sqrt{25} }[/tex]

=> [tex]E =3.92 *10^{-5} [/tex]

The 95% confidence level is mathematically represented as

[tex]\= x - E < \mu < \= x + E[/tex]

=> [tex]0.5046 - 3.92 *10^{-5} < \mu < 0.5046 + 3.92 *10^{-5} [/tex]

=> [tex]0.5045608 < \mu < 0.5046392 [/tex]

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