Assume that cholesterol levels for Adults in the US are normally distributed wit

Question

Assume that cholesterol levels for Adults in the US are normally distributed with a mean of 190 and a standard deviation of 20.

a) What is the probability that a randomly selected adult will have a cholesterol level exceeding 240?

b)What is the probability that a randomly selected adult will have a cholesterol level below 200?

c) Let Y be the random variable representing the cholesterol level for a randomly selected adult. explain in words what each of the following probabilities represent. (you don't need to calculate them)

(I) P(Y=195)

(ii) P(170<Y<220)

Explanation / Answer

as z=(X-mean)/std deviation

hence a) P(X>240) =1-P(Z<(240-190)/20) =1-P(Z<2.5)=1-0.9938 =0.0062

b)P(X<200) =P(Z<0.5) =0.6915

c) P(Y=195) represent probability that a random indivdual has cholestrol lelvel equal to 195.

P(170<Y.<210) represent probability that a random indivdual has cholestrol level from 170 to 210.

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