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he distribution of cholesterol levels in teenage boys is approximately attention. Find the probability that a?
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he distribution of cholesterol levels in teenage boys is approximately normal with and (Source: U. S. National Center for Health Statistics). Levels above 200 warrant attention. Find the probability that a teenage boy has a cholesterol level greater than 225.
You have to find the upper percent (right-side of one-tailed) cut off by z corresponding to 225.
x = 225
z = (x – μ) / σ
If 15.6% of people have cholesterol level 200 mg/dL and over, p = 0.156
If we take a sample of n=1000 teenagers, the mean and standard deviation will be:
μ = n*p
μ = 1000*0.156 = 156
σ = √(n*p*(1-p))
σ = √(1000*0.156*0.844)=31.6
z = (225 – 156) / 31.6 = 2.1835
The upper area (http://www.measuringusability.com/pcalcz.php) is 1.45% or the probability will be 0.0145.