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 30.93 ng/mL with a standard deviation of 4.061 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 68% 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.
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