To solve a Venn diagram with 3 circles, start by entering the number of items in common to all three sets of data. Then enter the remaining number of items in the overlapping region of each pair of sets. Enter the remaining number of items in each individual set. Finally, use any known totals to find missing numbers.

For the Venn diagram: Step 1: Draw three overlapping circles to represent the three sets. Step 2: Write down the elements in the intersection X ∩ Y ∩ Z. Step 3: Write down the remaining elements in the intersections: X ∩ Y, Y ∩ Z and X ∩ Z. Step 4: Write down the remaining elements in the respective sets.