A large manufacturing plant has analzyed the amount of time required to produce

Question

A large manufacturing plant has analzyed the amount of time required to produce an electrical part and determined that the times follow a normal distribution with mean time =45 hours. The production manager has developed a new procudure for producing the part. He believes the new procedure will decrease the population mean amount of time requred to produce the part. After training a gorup of production line workers, a random sample of 25 parts will be selected and the average amount of time required to produce them will be determined. If the switch is made the new procedure, the cost to the implement the new procedure will be more than offset by the savings in manpower required to produce the parts. Use the hypothesis: H_0 If the sample mean amount of tim is x=43.118 hours and the sample standard deviation is s=5.5 hours, what is the lowest level of signficance?

a) a=5%

b) a=1%

c) a=10%

d) the manager should not adopt the new procedure

e) a=2%

Explanation / Answer

SOlution:

lowest level of signficance=lowest alpha=1%=0.01

H0:mu=45

Ha:mu<45

alpha=0.01

T=sample mean-pop mean/samplesd/sqrt(n)

=43.118-45/5.5/sqrt(25)

t=-1.71

df=n-1=25-1=24

p=0.0499

0.0499>0.01

Fail to reject Ho

Accept Ho

b) a=1%

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