Unformatted text preview: [M13326 Engineering Test Design and Analysis 6. Given a sampling distribution of the sample mean 3? that is normally distributed and has a
mean of 30 and a standard deviation of 8, a sample mean of 40 corresponds to a. a z llue of-1.25 Mine of +1.25
. a sample size of 120
d. a sample size of 300 7. An agricultural economist is interested in determining the average diameter of peaches
produced by a particular tree. A random sample of n = 30 peaches is taken and the sample
mean x—bar is calculated. Suppose that the average diameter of peaches on this tree is known from previous years’ production to be p= 60 millimeters with 0' = 10mm. What is the
probability that the sample mean, 3:, exceeds 65 millimeters? 65 ; 292$) fwmfpgk:
témgz Xi aw i 8. A controversial issue in the state of California is the diversion of water ﬁ-orn northern to
southern regions of the state. Suppose that 30% of the population favor‘the diversion, while
70% oppose it. If a random sample of voters is taken, what is the probability that 50% or
more favor the diversion? That is, what is the probability that the sample will show a majority in favor of the diversion when in fact only 30% of the population favor it?
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