A government sample survey plans to measure the LDL (bad) cholesterol level of a

Question

A government sample survey plans to measure the LDL (bad) cholesterol level of an 5RS of men aged 20 to 34 Suppose that in fact the LU o-25 mg/dL Use Table A for the following questions, where necessary DL cholesterol level of all men aged 20 to 34 follows the Normal dstribution with mean . 113 maigrams per dediter (mg/A) and standard deviation SRS of 100 men from this population. What is the sampling distribution of (Use the urits of ma/al.) N( 113, 25) N(0.113, 0.025) N(113, 25) O N(113, 0.25) O N(1.13, 0.25) Round your am er to three deci al places what is the probably thi tr tales a value between i u and us mg/dL? This is the probability that x estimates within t2 mg a (b) Choose an SRS of 1000 men from this population. Kwis theprobahtfals whin 12 mg/d od yo The larger sampele is mouch more Bely to give an accurate estimate of .(Use Table A and round your answer to 3 decimal places.)

Explanation / Answer

Sol:

X follow normal distribution with mean=113 and sd=25

x bar  follow normal distribution with mean=113 and sd=25/sqrt(sample size)

N~(mean,sd)

N~(113,25/sqrt(100)

N~(113,2.5)

OPTION A FROM GIVEN CHOICES

Solutionb:

P(111<X<115)

p(111-113/25/sqrt(100)<Z<115-113/25/sqrt(100))

P(-2/2.5<Z<2/2.5)

P(-0.8<Z<0.8)

P(Z<0..8)-P(Z<-0.8)

pnorm(0.8)-pnorm(-0.8)

0.5762892

0.576( to 3 decimals)

ASNWER:0.576

Solutionc:

p(111-113/25/sqrt(1000)<Z<115-113/25/sqrt(1000))

P(-2.53<Z<2.53)

pnorm(2.53)-pnorm(-2.53)

= 0.9885937

ANSWER:0.989

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