Body mass index (BMI) is a reliable indicator of body fat for most children and teens. BMI is calculated from a child’s weight and height and is used as an easy-to-perform method of screening for weight categories that may lead to health problems. For children and teens, BMI is age- and sex-speciic and is often referred to as BMI-for-age.

The Centers for Disease Control and Prevention (CDC) reports BMI-for-age growth charts for girls as well as boys to obtain a percentile ranking. Percentiles are the most commonly used indicator to assess the size and growth patterns of individual children in the United States.

The following table provides weight status categories and the corresponding percentiles and BMI ranges for 10-year-old boys in the United States.

Health officials of a mid western town are concerned about the weight of children in their town. For example, they believe that the BMI of their 10-year-old boys is normally distributed with mean 19.2 and standard deviation 2.6.
In a report, use the sample information to:
1. Compute the proportion of 10-year-old boys in this town that are in the various weight status categories given the BMI ranges.
2. Discuss whether the concern of health officials isjustified.

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BMI Range Weight Status Category Underweight Healthy Weight Overweight Obese Percentile Range Less than 5th Between 5th and 85th Between 14.2 and 19.4 Between 85th and 95th Between 19.4 and 22.2 More than 95th Less than 14.2 More than 22.2