How do you use a TI-89 to get phi(z) when you do a confidence interval, i.e.(adsbygoogle = window.adsbygoogle || []).push({});

phi(z) = 1/2 (1 + erf(z / sqrt(2)))

The Normal CDF function has lower and upper values so I don't see how I can do it, and erf(z) doesn't do anything when I enter it so it must not be built in. Integrating the error function doesn't work either, I think because it's nonstandard.

ex - using TI 89 to calculate phi(4.5) = .999997

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# Calculators Using TI-89 for confidence intervals

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