EXAMPLE 1.3.2

A survey of used car salesmen revealed the following information:

24 wear white patent-leather shoes

28 wear plaid trousers

20 wear both of these things

2 wear neither of these things

1. How many were surveyed?

2. How many wear plaid trousers but don't wear white patent-leather shoes?

SOLUTION

Let S represent those who wear white patent-leather Shoes.

Let T represent those who wear plaid Trousers.

We have this Venn diagram:

"20 wear both of these things:"

"24 wear white patent-leather shoes:"

"28 wear plaid trousers:"

"2 wear neither of these things"

1. How many were surveyed?

We add all four numbers in the diagram:

4 + 8 + 20 + 2 = 34

2. How many wear plaid trousers but don't wear white patent-leather shoes?

The diagram shows that the answer is "8."