Question 925287
Ho:  μ = 0 
Ha:  u ≠ 0
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n = 18
sample mean = -.139  and s = .324
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level of .02 significance.  Using z critical value
ME = 2.326(.324/sqrt(18)  
CI: -.178 < 0 < .178
Note: small sample (DF = 17) ..may wish to use t-value( for critical value 
..........
test stat = -.139/(.324/sqrt(18)) = -1.82