The Practically Cheating Statistics Handbook ti-83 Companion Guide

Step 1: Press to get the DISTR option. Press for binomPDF.
Step 2: Enter the number of trials from the question. Sue bats three
times, so the number of trials is 3. Press and hit the key.
Step 3: Enter the Probability of Success, P. Sue’s batting average is
.240, so enter , then hit the key.
Step 4: Enter the X value. We want to know Sue’s chances of getting
exactly two hits, so enter and then press .
Step 5: Press for the result. Sue’s chances of getting exactly two hits is
.159651.
Warning: BinomialPdf is an exact probability for one value of x. If you
want to find a cumulative probability (for example, what are John’s chances
of getting 0 or 1 hits?) you will need the use the BinomialCdf function.

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Normal Distributions
Central Limit Theorem

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The TI 83 calculator has a built in function that can help you calculator
probabilities of central theorem word problems. The function, normalcdf,
requires you to enter a lower bound, upper bound, mean, and standard
deviation.¶
Sample problem: A fertilizer company manufactures organic fertilizer in 10
pound bags with a standard deviation of 1.25 pounds per bag. What is the
probability that a random sample of 150 bags will have a mean between 9
and 9.5 pounds?
Step 1: Press .
Step 2: Enter your variables (lower bound, upper bound, mean, and
standard deviation): .
Step 3: Press . This returns the probability of .159, or 15.9%.
Tip: Sampling distributions require that the standard deviation of the mean
is σ / √(n), so make sure you enter that as the standard deviation.

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