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The American Carbon Registry, www.americancarbonregistry.org, provides approved

ID: 3153933 • Letter: T

Question

The American Carbon Registry, www.americancarbonregistry.org, provides approved measurement methodologies for energy companies who wish to show greenhouse gas emission reduction through retrofitting high-bleed pneumatic controllers with low-bleed controllers. Summary sample data from the two manufacturers are shown in the table below. Are the variances of the two manufacturers equal?

s2 = 237.9             

Choose the appropriate hypotheses. Assume 12 is the variance of the manufacturer Cemco and 22 is the variance of the manufacturer Invalco.

Calculate the critical values for = 0.10. (Round your answers to 3 decimal places.)

  

                     s1 = 147.2            

s2 = 237.9             

a)

Choose the appropriate hypotheses. Assume 12 is the variance of the manufacturer Cemco and 22 is the variance of the manufacturer Invalco.

a. H0: 12 / 22 = 1vs. H1: 12 / 22 1 b. H0: 12 / 22 1vs. H1: 12 /22 = 1 a b (b)

Calculate the critical values for = 0.10. (Round your answers to 3 decimal places.)

     FR   FL (c) Calculate the test statistic Fcalc. (Round your answer to 3 decimal places.)
  Fcalc (d) What is your conclusion?

  

  We (Click to select)cancannot conclude that the variances are not equal n1 = 18                 n2 = 17                 

Explanation / Answer

Here we are given that,

X1bar = 510.5

X2bar = 628.9

s1 = 147.2

s2 = 237.9

n1 = 18

n2 = 17

Choose the appropriate hypotheses. Assume 12 is the variance of the manufacturer Cemco and 22 is the variance of the manufacturer Invalco.

H0: 12 / 22 = 1 vs. H1: 12 / 22 1

Option a) is correct.

Calculate the critical values for = 0.10.

= 0.10.

Critical value in F distribution we can find by using EXCEL.

syntax :

=FINV(probability, deg_freedom1, deg_freedom2)

probability = alpha/2

deg_freedom1 = n2-1 = 17-1 = 16

deg_freedom2 = n1-1 = 18-1 = 17

Critical value = 2.289

Calculate the test statistic Fcalc

Fcalc = largest variance / smallest variance

= s22 /s12

= 237.92 / 147.22

= 2.612

What is your conclusion?

Fcalc > critical value

Reject H0 at 10% level of significance.

Conclusion : The two variances are not equal.

a)

Choose the appropriate hypotheses. Assume 12 is the variance of the manufacturer Cemco and 22 is the variance of the manufacturer Invalco.

H0: 12 / 22 = 1 vs. H1: 12 / 22 1

Option a) is correct.

(b)

Calculate the critical values for = 0.10.