Question 327333
What is the z-value for a two tailed hypothesis test on a population mean when alpha is 5%
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Sketch a standard normal distribution curve 
with z as its horizontal axis.
Sketch a 95% area centered on the mean value,
which is 0.
That leaves a left-tail of 2.5% on the left
and a right-tail of 2.5% on the right.
The cut-off point on the left and on the right
is 1.96 standard deviations from the center at
+1.96 and at -1.96.
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Cheers,
Stan H.
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a) z=1.65
b) z=1.96
c) z=2.33
d) z=2.58