# Normal distribution calculator

Enter mean (average), standard deviation and cutoff points and this normal distribution calculator will calculate the area (=probability) under normal distribution curve.### How to enter data as frequency table?

Simple. First-type data elements (separated by spaces or commas etc) then type f: and further write frequency of each data item. Each element must have defined frequency that number of numbers before and after symbol f: must be equal. For example:1.1 2.5 3.99

f: 5 10 15

### How to enter data as cummulative frequency table?

Similar as frequency table, but instead f: type cf: in second line. For example:10 20 30 40 50 60 70 80

cf: 5 13 20 32 60 80 90 100

The cumulative frequency is calculated by adding each frequency from a frequency distribution table to the sum of its predecessors. The last value will always be equal to the total for all observations, since all frequencies will already have been added to the previous total.