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# Exam1_key - NAME ANSWER KEY Stat 205 Exam I There are four...

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NAME: ANSWER KEY Stat 205 Exam I There are four problems total. Each lettered part of a problem is worth 7 points; there are 126 points total. However, your exam grade is out of 100 points, so there are 26 points of possible extra credit. Write clearly and show steps for partial credit. This exam is open book. 1. The systolic blood pressure Y of a random American adult follows a normal distribution with mean μ Y = 127 mmHg and standard deviation σ Y = 15 mmHg. Hypertension is deﬁned to be Y > 140 ; hypotension (low blood pressure) is Y < 90 . (a) What is the probability of a randomly selected person having hypertension, P ( Y > 140) ? Answer: Using TI-84, normalcdf(140,10 99,127,15) gives 0.193. Using the table in your book, P ( Y > 140) = P ± Y - 127 15 > 140 - 127 15 = P ( Z > 0 . 87) = 1 - P ( Z < 0 . 87) = 1 - 0 . 8078 0 . 192 . (b) What is the probability of a randomly selected person having low systolic blood pres- sure, P ( Y < 90) ? Answer: Using TI-84, normalcdf( - 10 99,90,127,15) gives 0.007. Using the table in your book, P ( Y < 90) = P ± Y - 127 15 < 90 - 127 15 = P ( Z < - 2 . 45) = 0 . 007 . (c) What is the probability of a randomly selected person having normal systolic blood pressure, P (90 < Y < 140) ? Answer: Using TI-84, normalcdf(90,140,127,15) gives 0.800. Using the table in your book, P (90 < Y < 140) = P ± 90 - 127 15 < Y - 127 15 < 140 - 127 15 = P ( - 2

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Exam1_key - NAME ANSWER KEY Stat 205 Exam I There are four...

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