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Finding the Critical Value; $90\%$ Confidence

APSTAT-ETKEZ4

You want to compute a $90\%$ confidence interval for the mean population with an unknown standard deviation. The data is collected from an SRS of $20$ observations, and it is approximately normal.

What critical value would we need for the $90\%$ confidence interval?

A

$1.645$

B

$1.721$

C

$1.725$

D

$1.729$

E

$1.734$