1) BMI calculation
Subject      A                                B                                  C
Age           57                                30                                18
Gender      Male                           Male                            Male
heigth        70 in                            72 in                            68
                  70 * 2.54 = 177.8cm   72*2.54=182.88cm     68*2.54=172.72 cm
weight       165 lb              190 lb                       185 lb
         165/2.2046=74.8kg    190/2.2046=86.2kg    185/2.2046=83.9kg
BMI Â Â Â Â Â Â 74.8*10,000Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 86.2*10,000Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 83.9*10,000
         = 23.7     = 25.8   = 28.1
           (177.8)^2            (182.88)^2                 (172.72)^2
2) Weight status
Subject A: 18.5 ≤ 23.7 ≤ 24.9 => Considered Ideal
Subject B: 20.5 ≤ 25.8 ≤ 29.9 => Considered Overweight
Subject C: 20.5 ≤ 28.1 ≤ 29.9 => Considered Obese
Ideal weight range
Inequality
       w * 10,000                  18.5*h^2              24.9*h^2
 18.5 ≤ ≤ 24.9 => ≤ w ≤  Â
               h^2                          10,000                  10,000
Subject A: h = 177.8 cm =>
18.5*(177.8)^2Â Â Â Â Â Â Â Â Â Â 24.9*(177.8)^2
≤ w ≤
    10,000                     10,000
         58.5 kg ≤ w ≤ 78.7
Subject B: h = 182.88 cm
           Â
18.5*(182.88)^2Â Â Â Â Â Â Â Â Â Â 24.9*(182.88)^2
   ≤ w ≤
    10,000                         10,000
         61.9 kg ≤ w ≤ 83.3
Subject C:
18.5*(172.72)^2Â Â Â Â Â Â Â Â Â Â 24.9*(172.72)^2
≤ w ≤
    10,000                      10,000
         55.2 kg ≤ w ≤ 74.3 kg
3) Is BMI an appropiate measure of health?
Pros:
* it is quick and easy to calculate, so it provides a prompt measure.
Cons:
* It is not accurate.
* It leaves out specific conditions of the person: genetic and fitness.
I like that it provides a standardization to compare the status of different persons based on an objective measure, but you need to include other factors: age, gender, build, fat %, activities performed, among others. So, I am in favor of using it only like a factor but you need to use other additional measures.
