A plating company has two silver plating systems with variances σ12 and σ22. You, as the manager, desired to compare the variability in the silver plating done by System-1 with that done by System-2. An independent random sample of size n1= 12 of the System-1 yields s1 = 0.038 mil and sample of size n2= 10 of System-2 yields s2 = 0.042 mil. We need to decide whether σ12= σ22 with α = 0.05. What is the rejection region?

Respuesta :

Answer:

The  rejection region is

       [tex]F_{cal} < F_{{1-\frac{\alpha}{2}} , df_1 , df_2 }[/tex]

or     [tex]F_{cal} > F_{{\frac{\alpha}{2}} , df_1 , df_2 }[/tex]

and  

From the value obtained we see that  

[tex] F_{cal} <   F_{\frac{\alpha }{n} , df_1 , df_2 } [/tex]    Hence

    The decision rule

Fail to reject the null hypothesis

The conclusion

This no sufficient evidence to conclude that there is a difference between the two variance

Step-by-step explanation:

From the question we are told that

   The first sample size is  [tex]n_1 =  12[/tex]

   The first sample standard deviation is [tex]s_1 =  0.038 \  mil[/tex]

   The second sample size is  [tex]n_2 =  10[/tex]

   The first sample standard deviation is [tex]s_2 =  0.042 \  mil[/tex]

    The significance level is  [tex]\alpha =0.05[/tex]

The null hypothesis is [tex]H_o : \sigma^2_1  = \sigma^2_2[/tex]

The alternative hypothesis is   [tex]H_o : \sigma^2_1 \ne  \sigma^2_2[/tex]

Generally the test statistics is mathematically represented as

        [tex]F_{cal} =  \frac{s_1^2 }{s_2^2}[/tex]

=>     [tex]F_{cal} =  \frac{ 0.038^2 }{0.042^2}[/tex]

=>     [tex]F_{cal} =  0.81859[/tex]    

Generally the first degree of freedom is  [tex]df_1 =  n_1 -1  =  12-1 = 11[/tex]

Generally the second degree of freedom is  [tex]df_2 =  n_2 -1  =  10 -1 = 9[/tex]

From the F-table the critical  value of  [tex] \frac{\alpha}{2}[/tex] at the degrees of freedom of   [tex]df_1 = 11[/tex]  and   [tex]df_2 =9 [/tex] is  

         [tex]F_{\frac{\alpha }{n} , df_1 , df_2 } =  3.91207[/tex]

The  rejection region is

       [tex]F_{cal} < F_{{1-\frac{\alpha}{2}} , df_1 , df_2 }[/tex]

or     [tex]F_{cal} > F_{{\frac{\alpha}{2}} , df_1 , df_2 }[/tex]

and  

From the value obtained we see that  

[tex] F_{cal} <   F_{\frac{\alpha }{n} , df_1 , df_2 } [/tex]    Hence

    The decision rule

Fail to reject the null hypothesis

The conclusion

This no sufficient evidence to conclude that there is a difference between the two variance