Perfluorooctanoic acid (PFOA) is a chemical used in products that coat cookware

Question

Perfluorooctanoic acid (PFOA) is a chemical used in products that coat cookware to prevent food from sticking. An agency is investigating the potential risk of PFOA as a cancer-causing agent. It is known that the blood concentration of PFOA in the general population has a mean of = 6 parts per billion (ppb) and a standard deviation of = 10 ppb. An article reported on tests for PFOA exposure conducted on a sample of 323 people who live near a factory that makes one such nonstick cookware product. Complete parts (a) and (b) below. Click the icon to view the table of normal curve areas. a. What is the probability that the average blood concentration of PFOA in the sample is greater than 7.5 ppb? P(x> 7.5)(Round to three decimal places as needed.) b. The actual study resulted in x 300 ppb. Use this information to make an inference about the true mean (H) PFOA concentration for the population that lives near the factory. A, OB, >300 -300

Explanation / Answer

the PDF of normal distribution is = 1/ * 2 * e ^ -(x-u)^2/ 2^2
standard normal distribution is a normal distribution with a,
mean of 0,
standard deviation of 1
equation of the normal curve is ( Z )= x - u / sd/sqrt(n) ~ N(0,1)
mean of the sampling distribution ( x ) = 6
standard Deviation ( sd )= 10/ Sqrt ( 323 ) =0.5564
sample size (n) = 323
a.
GREATER THAN
P(X > 7.5) = (7.5-6)/10/ Sqrt ( 323 )
= 1.5/0.556= 2.6958
= P ( Z >2.6958) From Standard Normal Table
= 0.0035

b.
Option D. U > 6

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