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Too much cholesterol in the blood increases the risk of heart disease. The cholesterol levels of young women age 20 to 34 have an approximate Normal distribution with mean 185 milligrams per deciliter (mg/dL) and standard deviation 
39mg//dL.
About what percent of young women in this age group will have cholesterol levels less than 
150mg//dL ?

82%

90%

18%

Too much cholesterol in the blood increases the risk of heart disease. The cholesterol levels of young women age 2020 to 3434 have an approximate Normal distribution with mean 185185 milligrams per deciliter (mg/dL) and standard deviation 39mg/dL 39 \mathrm{mg} / \mathrm{dL} .\newlineAbout what percent of young women in this age group will have cholesterol levels less than 150mg/dL 150 \mathrm{mg} / \mathrm{dL} ?\newline82% 82 \% \newline90% 90 \% \newline18% 18 \%

Full solution

Q. Too much cholesterol in the blood increases the risk of heart disease. The cholesterol levels of young women age 2020 to 3434 have an approximate Normal distribution with mean 185185 milligrams per deciliter (mg/dL) and standard deviation 39mg/dL 39 \mathrm{mg} / \mathrm{dL} .\newlineAbout what percent of young women in this age group will have cholesterol levels less than 150mg/dL 150 \mathrm{mg} / \mathrm{dL} ?\newline82% 82 \% \newline90% 90 \% \newline18% 18 \%
  1. Identify parameters: Identify the parameters of the normal distribution.\newlineMean μ\mu = 185185 mg/dL\newlineStandard Deviation σ\sigma = 3939 mg/dL\newlineWe need to find the probability that cholesterol levels are less than 150150 mg/dL.
  2. Calculate Z-score: Calculate the Z-score for 150mg/dL150\,\text{mg/dL}. \newlineZ=XμσZ = \frac{X - \mu}{\sigma}\newlineZ=15018539Z = \frac{150 - 185}{39}\newlineZ=3539Z = \frac{-35}{39}\newlineZ0.897Z \approx -0.897
  3. Use Z-score: Use the Z-score to find the corresponding percentile from the standard normal distribution table. Looking up Z=0.897Z = -0.897, we find that the percentile is approximately 18%18\%.

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