S Firefox File Edit View History Bookmarks Tools Window Help Review Test Kendon

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S Firefox File Edit View History Bookmarks Tools Window Help Review Test Kendon Spering httpselNwww.mathxi.com/student/PlayerTest.aspx?TestResultld-599007389&review; yes&questionldm1; STAT 211 Section 022 Spring 2017 Review Test: Exam 1 Practice (assignment grade will not be Close counted) Score: 0.8 of 1 pt 13 of 16 Test Score: 61.86%, 9.9 of 1 5.1.47 The cholesterol levels of an adult can be described by a normal model with a mean of 182 mg/dL andastandard deviation a) Draw and label the normal model. bo what percent of adults do you expect to have cholesterol levels over 190 mg/dL? 37 83% (Round to two decimal places as needed.) c) What percent of adults do you expect cholesterol levols between 140 and 160 mg/dL? to have (Round to two decimal places as needed) d)Estimate the interquartile range of cholesterol levels is complete. Tap on the red indicators MacBook Ai

Explanation / Answer

Answer to part a)

Given:

Normal distribution with mean = 182 & SD = 26

Thus the correct curve would show the readings:

(182-3*26) , (182-2*26) , (182-26) , 182 , (182+26) , (182+2*26) , (182+3*26)

104 , 130 , 156 , 182 , 208 , 234 , 260

Thus the correct noraml curve is c

.

Answer to part b)

P(x > 190) = 1 - P(X < 190)

P(X < 190) = P(z < (190-182)/26)

P(x < 190) = P(Z < 0.31)

From the Z table we get to know:

P(x < 190) = P(Z < 0.31) = 0.6217

.

Thus P(x > 190) = 1 - 0.6217 = 0.3783

.

Answer to part c)

P(140 < x < 160) = P(x < 160) - P(x < 140)

P(x < 160) = P(z < 160-182/26) = P(z < -0.85) = 0.1977

P(x < 140) = P(z < 140-182/26) = P(z < -1.62) = 0.0526

.

Thus P( 140 < x < 160) = 0.1977 - 0.0526 = 0.1451

.

Answer to part d)

For interquartile range we need to find q1 and q3

q1 corresponds to 25th percentile and q3 corresponds to 75th percentile

So from the Z table we can find the Z values corresponding to 0.2500 and 0.7500 areas

We get Z(q1) = -0.675

Z(q3) = +0.675

Thus we can plug these values in the formula of Z

Z(q1) = (x-M) / SD

-0.675 = (q1 - 182) / 26

q1 = 164.45

.

Z(q2) = (q2-M) / SD

0.675 = (q2 - 182) / 26

q2 = 199.55

.

thus interquartile range = q3 - q1 = 199.55 - 164.45 = 35.1

Thus IQR = 35.10

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