In a recent survey of 100 women, the following information was gathered.

You'll find several answers in the Related Questions below.

To find the number of women using shampoos A and C, but not B (Region IV), we need to calculate the number of women who use both shampoos A and C and then subtract the number of women who use shampoos A, B, and C.

Let's break down the given information step by step:

- 53 women use shampoo A
- 31 women use shampoo B
- 31 women use shampoo C
- 4 women use shampoos A and B
- 10 women use shampoos A and C
- 13 women use shampoos B and C
- 3 women use all three shampoos (A, B, and C)

Now, let's calculate the number of women using shampoos A and C, but not B:

1. Add the number of women who use shampoos A and C: 10

2. Subtract the number of women who use all three shampoos (A, B, and C): 3

Therefore, the number of women using shampoos A and C, but not B (Region IV), is 10 - 3 = 7.