Formula sheet · Grades 11 to 12

Statistics formulas

10 formulas from this course. Each one gives the rule in math, one line on what it means, and a worked example that uses it.

Mean

\bar{x} = \frac{\sum x}{n}

Add every value, then divide by how many values there are.

\bar{x} = \frac{\sum f x}{\sum f}

Multiply each value by its frequency, add, then divide by the total frequency.

\text{middle value of the ordered list}

Sort the values first, then take the middle one.

\text{most frequent value}

The value that appears most often in the data set.

\text{range} = \max - \min

The largest value minus the smallest value.

\text{midrange} = \frac{\max + \min}{2}

The halfway point between the largest and smallest values.

\text{total} = \bar{x} \times n

Multiply the mean by the count to rebuild the total, then find a missing value.

P(A) = \frac{\text{favourable outcomes}}{\text{total outcomes}}

Count the outcomes you want and divide by all equally likely outcomes.

P(\text{not } A) = 1 - P(A)

The chance an event does not happen is 1 minus the chance it does.

P(A \text{ and } B) = P(A) \times P(B)

Multiply the probabilities when one event does not affect the other.

Practice problems with answers for every Statistics topic.