SOLUTION: A random sample of twelve floor jacks is taken and the variable x represents the weight at which each jack fails under successively heavier loading (called the �failure rate of the

Question 929450: A random sample of twelve floor jacks is taken and the variable x represents the weight at which each jack fails under successively heavier loading (called the �failure rate of the jack�) is recorded. The sample mean for the 12 recorded weights was 17.1 with a standard deviation of 5.41 tons. Assuming that the population of failure weights for all such jacks is normally distributed, what is the critical value required to form a 95% confidence interval (see attached graphic) for the mean failure weight for all such jacks?
17.1+-(Critical Value) 5.41/sqrt(12)

A 1.782
B 1.796
C 1.960
D 2.179
E 2.201
Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!

 

Hi

CI	

90%	z =1.645

92%	z = 1.751

95%	z = 1.960

98%	z = 2.326

99%	z = 2.576

.....

z = 1.960

C.

 

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