Question

The average body mass index value of children 9 years old is 18.4 with a standard deviation of 4.5. If it is known that the distribution is approximately normal, what is the body mass index for a 9-year-old child at the 82nd percentile?

Answer 1

Solution:
Given in the question
the body mass index for a 9-year-old child s approximately normal with
Mean () = 18.4
Standard deviation() = 4.5
We need to calculate the body mass index for a 9-year-old child at the 82nd percentile
So p-value = 0.82
From Z table we found Z-score = 0.91537
So body mass index for a 9-year-old child can be calculated as
Body mass index = + Z-score * = 18.4 + 0.91537*4.5 = 18.4 + 4.12 = 22.52
So the body mass index for a 9-year-old child at the 82nd percentile is 22.52