42. Select one: A. LCL=85 UCL=95 B. LCL=74 UCL=86 C. LCL=80 UCL=110 D. LCL=20 UC

Question

42.

Select one:

A. LCL=85 UCL=95

B. LCL=74 UCL=86

C. LCL=80 UCL=110

D. LCL=20 UCL=170

44.An electric company operates a fleet of trucks that provide electrical service to the construction industry. Monthly maintenance cost has been $75 per truck. A random sample of 16 trucks provided a sample mean maintenance cost of $82.50 per month, with a sample standard deviation of $30. Using a 5% level of significance, You like to see whether the mean monthly maintenance cost has increased. Set the appropriate hypotheses and calculate the test statistic

Select one:

A. Z=+1

B. t=+1

C. Z=1

D. t=1

Explanation / Answer

42)UCL and LCL are calculated at 3 standard deviations

Hence LCL=95-3*25/sqrt(25)=80

UCL=95+3*25/sqrt(25)=110

44)as sample size is 16 which is less than 30,we have a t statistic

hence t=(82.5-75)/(30/sqrt(16))=1

hence t=1

I really donno whats the difference between t=1 and t=+1.I think both are the same

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