The results of the class survey were used to create a data set for our fuzzy function. Using students' responses for height and weight, we calculated the Body Mass Index (BMI). The BMI is used by health care professionals to determine a person's appropriate or " healthy " weight. A BMI between 20 and 25 is considered healthy.

The following fuzzy function was used to calculate membership values for the set healthy. A membership value of 1 is healthy; a membership value of 0 is not healthy; a membership value between 0 and 1 is the degree of membership in the healthy set.

healthy(x) =	{ 0,	if bmi(x) < 18
	(bmi(x)-18)/2,	if 18 <= bmi(x) <= 20
	1,	if 20 < bmi(x) < 25
	(27-bmi(x))/2,	if 25 <= bmi(x) <= 27
	0,	if bmi(x) > 27 }

After the membership values were calculated, the values were graphed. The results are presented in the graph below.

BMI values that range from 20 to 25 are members of the healthy set (1). BMI values greater then 27 or less then 18 are not members of the healthy set (0). BMI values close to the healthy range (20 to 25) are a value between 0 and 1. For example, a BMI val ue of 19.6 is 0.8 degree of membership in the healthy set.

Want to calculate your BMI? Use the calculators below to determine your Body Mass Index.

Calculate Body Mass Index using Feet and Pounds

Enter your height:	feet:.... inches:
Enter your weight:	pounds:
Your result:

Calculate Body Mass Index using Meters and Kilograms

Enter your height in meters:
Enter your weight in kilograms:
Your result:

Now that you know your BMI, you can calculate your degree of membership for the healthy set. Use the function listed above. Here are a few examples to get you started:

BMI	Membership Value
17	0
19	0.5
23	1
26	0.5
33	0

What's your degree of membership in the set healthy?

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