Question

A research study examined the blood vitamin D levels of the entire US population of landscape gardeners. The population average level of vitamin D in US landscapers was found to be 54.8 ng/mL with a standard deviation of 5.268 ng/mL. Assuming the true distribution of blood vitamin D levels follows a normal distribution, what is the lower value of the region for which approximately 99.9% of the data are located within the distribution? Recall the 68-95-99.9% observation discussed in the “Normal Distribution” section of the textbook that is helpful in answering the question

Answer 1

99.9% of data falls with in 3 standard devaitions of mean.

=(54.8±3*5.268)

=(38.996,70.604)

lower limit=38.996