TI-83 plus help???

Question

How do you calculate the z-score using the calculator and calculate the percent using the z-score in the calculator?

Answer 1

The normal pdf and cdf are both available under 'distr'. It's a yellow button prefix on the 'vars' button.

The formats are:

normalcdf(lowerbound,upperbound [,mu,sigma])
mu and sigma are optional, if omitted 0 and 1 are assumed, ie, standard normal

normalpdf(x [,mu,sigma])

You can download a users manual from a Texas Instruments website.

Answer 2

I don't have an 83, but here's my guesses:
1) Find some sort of "NormalCDF" function
2) Have it approximate the integral of the first equation found in the link below. Note that if you're finding something like P(z>1.96) you would need to integrate from 1.96 to infinity.

(And the z-score is just given by z = [(x-mu)/sigma].)