Suppose a subdivision on the southwest side of Denver, Colorado, contains 1, 500

Question

Suppose a subdivision on the southwest side of Denver, Colorado, contains 1, 500 houses. The subdivision was built in 1983. A sample of 100 houses is selected randomly and evaluated by an appraiser. If the mean appraised value of a house in this subdivision for all houses is $227,000 with a standard deviation of $8, 500, what is the probability that the sample average is greater than $229,000? N = _________ n = _________ = ______ = __________ z = __________ = _______ According to a study by Decision Analyst, 21% of the people who have credit cards are very close to the total limit on the card(s). Suppose a random sample of 600 credit card users is taken. What is the probability that more than 150 credit card users are very close to the total limit on their card(s)? n = _________ x = ________ p = ________ Check: __________ z = ________ = __________-

Explanation / Answer

a) N=1500 ; n=100

mean =227000

std error of mean =std deviation/(n)1/2 =850

hence P(X>229000)=1-P(Z<(229000-227000)/850)=1-0.9907=0.0093

2) n=600; x=150; p=0.21

here mean =np=600*0.21 =126

and std deviation =(np(1-p))1/2 =9.977

ehnce P(X>150)=1-P(X<=149)=1-P(Z<(149.5-126)/9.977)=1-P(Z<2.3554)=1-0.9907 =0.0093

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