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ID: 3281789 • Letter: P
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pls i need a professional to help me answer this question as fast as you can. Thanks you so much
Chapter 5 Practice Problems Sampling Distribution of Mean 1: Suppose you want to determine if there are differences in the average prices among items at three local supermarket chains. To reduce bias, how should you select the items to use in your study? a) Choose items which you know are commonly purchased. b) Rand omly select an appropriate number of times from a list of all possible items in the supermarket c) Choose only brand-name items. Problem 2: We make 1000 random observations from a population with a mean ofu 4 and a variance of 2-8 and calculate the i a) What do you know about the distribution of each observation? b) What do you know about the distribution of 3? c) Can you estimate the probability of R> 5.5? If yes, what is it; and if not, what do you need? d) Can you estimate the probability of X > 5.52 If yes, what is it; and if not, what do you need? 16,179 MacBook Air 3 4 5 8 9Explanation / Answer
Solution2a:
since sample size =n=1000
it is large sample since it is n>30
According to central limit theorem
Distribution is normal distribution.
Solution2b:
distribution of sample mean follows normal distribution
with sample mean=population mean
=4
sample std deviation=population stddev/sqrt(sample size)
=sqrt(8)/sqrt(1000)
=sqrt(8/1000)
=0.08944272
Solution2c:
P(X bar>5.5)
P(sampl mean)>5.5
z=xbar-mu/sigma/sqrt(n)
=5.5-4/sqrt(8/sqrt(1000)
=1.5/0.08944272
= 16.77051
P(Z>16.77051)=1-P(Z<16.77051)
=1-1
=0
ANSWER:0
Solutiond:
P(X>5.5)
z=x-mean/sd
=5.5-4/sqrt(8)
=1.5/2.828427
=0.5303301
P(Z>0.5303301) to be found
by using R
pnorm (-0.5303301)
=
0.2979415
ANSWER:0.2979415
ANSWER:0.2979415
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