QuestionUnit 2: The Normal Distribution L4 Practice - The Standard Normal Curve Name: $\qquad$ Hamahtlargus 1) Scores on the Wechsler Adult Intelligence Scale, a standard IQ test, are approximately Normal for the age group of 20 to 34 . The mean score is 110 with a standard deviation of 25 . What percent of this age group has an IQ below 100 ? $$P=(-.28<z<.35)$$ a) Write the inequality using the raw score. b) Find the $z$-score and rewrite the inequality. $$\text { ?. } P\left(\quad z=\frac{\frac{100-10}{25}}{z=-.4}\right.$$ c) Draw the Normal standardized curve. d) What are you entering into your calculator? $$z=\frac{20-110}{25}=-3.6 \quad z=\frac{34-110}{25}=-3.04$$ e) $34,4 \%$ of adults from 20 to 34 have an IQ less than 100 . 2) The distribution of blood cholesterol levels in 14 -year-old boys is roughly normal; the mean is 165 milligrams of cholesterol per deciliter of blood and the standard deviation is 30 . What proportion of 14 -year-old boys have a blood cholesterol level over $120 \mathrm{mg} / \mathrm{dl}$ ? a) Write the inequality. $$P 1$$ c) Draw the Normal standardized curve. b) Find the $z$-score and rewrite the inequality. $$z=\frac{120-165}{30}=-1.5$$ d) What are you entering into your calculator?
Lower: Upper: Mean $(\mu)$ : Standard Deviation $(\boldsymbol{\sigma})$ : e) $\qquad$ $\%$ of 14 -year-old boys have a blood cholesterol level over $120 \mathrm{mg} / \mathrm{dl}$.