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The Biology Project > Biomath > Rational Functions > Applications > Body Mass Index

Rational Function Applications

Body Mass Index

Rates of obesity have been steadily rising in the United States over the past two decades. This is a major health concern because obesity is a risk factor for a number of chronic illnesses including type II diabetes, heart disease, and high blood factor. But how do you classify someone as being obese? According to the (Centers for Disease Control) CDC, "Body Mass Index (BMI) is a number calculated from a person's weight and height. BMI is a reliable indicator of body fatness for people."

 

Photo credit: Clara Natoli

In particular, BMI classifies an adult person (20 years old or older) into one of the following categories,

BMI Classification
< 18.5
Underweight
18.5-24.9
Normal
25 - 29.9
Overweight
≥30
Obese

The equation used to calculate BMI is given by the rational function,

where w is a person's weight in pounds and h is a person's height in inches.

Use the formula to calculate BMI to answer the following questions:

Calculate the BMI given the person's height and weight.

Determine the maximum height of a person considered obese at a given weight.

Determine the BMI of a person given the height and weight.

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The Biology Project > Biomath > Rational Functions > Applications > Body Mass Index


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February 2007
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