## Forum archive 2000-2006

### Michael Gage - PGstatisticsmacros.pl ### Michael Gage - PGstatisticsmacros.pl

by Arnold Pizer -
Number of replies: 0 PGstatisticsmacros.pl topic started 9/14/2004; 2:20:59 PMlast post 9/14/2004; 2:20:59 PM Michael Gage - PGstatisticsmacros.pl 9/14/2004; 2:20:59 PM (reads: 1388, responses: 0)

# Statistics Macros

### Normal distribution

    Usage: normal_prob(a, b, mean=>0, deviation=>1);

Computes the probability of x being in the interval (a,b) for normal distribution. The first two arguments are required. Use '-infty' for negative infinity, and 'infty' or '+infty' for positive infinity. The mean and deviation are optional, and are 0 and 1 respectively by default. Load PGnumericalmacros.pl in your problem if you use this method.

### "Inverse" of normal distribution

    Usage: normal_distr(prob, mean=>0, deviation=>1);

Computes the positive number b such that the probability of x being in the interval (0,b) is equal to the given probability (first argument). The mean and deviation are optional, and are 0 and 1 respectively by default. Caution: since students may use tables, they may only be able to provide the answer correct to 2 or 3 decimal places. Use tolerance when evaluating answers. Load PGnumericalmacros.pl if you use this method.

###### File path = /ww/webwork/pg/macros/PGstatisticsmacros.pl

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