Venn diagrams are used to sort sets of data. The probability of an event not happening uses the complement of the region on the Venn diagram. Count the number of elements in each region. Redraw ...

John Venn: The man behind the famous diagrams – and why his work still matters today One of Venn’s major achievements was to find a way to visualise a mathematical area called set theory.

Venn had initially used diagrams developed by the Swiss mathematician Leonard Euler to show some relationships between sets, which he then developed into his famous Venn diagrams.