Computing Probabilities with TI Calculators and Excel:

TI83:

The TI-83 has lots of statistics functions built in. The cumulative distribution functions (aka CDFs, F(y) = Pr(X less than or equal to y) is the CDF.) are in the DISTR menu: press the 2^nd button and the DISTR button… More detailed instructions are in the “Distribution Functions” section of this pdf file (courtesy of the HP website): http://www.math.umass.edu/~jstauden/ti83prob.pdf

For other TI calculators, you need to add on the free statistics package. See http://education.ti.com/us/product/apps/89/statsle.html for the TI 89. (You may need to explore a bit if you have the TI 86.)

Microsoft Excel:

A few useful function names are: BINOMDIST, POISSON, NORMDIST, and HYPGEOMDIST

Examples:

X ~ binomial(n,p)

Pr(X=k) = BINOMDIST(k,n,p,0)

Pr(X<=k) = BINOMDIST(k,n,p,1)

X ~ Possion(r)

Pr(X=k) = POISSON(k,r,0)

Pr(X<=k) = POISSON(k,r,1)

X ~ Normal( mean = m, variance = v)

Pr(X<=k) = NORMDIST(k,m,sqrt(v),1) (Note that excel uses the standard dev instead of the variance…)

X ~ Hypergeometric( N,M,n )

Pr(X = k) = HYPGEOMDIST(k,n,M,N) (Note that excel puts the parameters in a different order than the distribution’s name. Also note that excel will not automatically compute a CDF for this distribution.)

Minitab:

Menu item:

Calc: Probability Distributions: Normal

Calc: Probability Distributions: Binomial

Calc: Probability Distributions: Poisson

etc.

Note that Minitab gives you the option to choose the CDF (cumulative button) or the PDF (probability button for discrete and probability density button for continuous distributions).