An investigator polls a representative sample of common cold sufferers, asking t

Question

An investigator polls a representative sample of common cold sufferers, asking them to estimate the number of hours of physical discomfort caused by their most recent cold. Their estimates approximate a normal curve with a mean of 83 hours and a standard deviation of 20 hour (Problems 6-10) 6.What percent of sufferers estimate that their colds lasted for longer than forty-eight hours? 7.What percent suffered for fewer than 61 hours? 8.What percent suffered for between one and three days? 9.What is the estimated number of hours for the shortest-suffering 10 percent? 10.A medical researcher wishes to concentrate on the 20 percent who suffered the most. She will work only with those who estimate that they suffered for more than _____hours.-

Explanation / Answer

=83hr

=20

a)

a)p(x>48)=1-p(x<=48)=1-0.04006=0.9599

b)p(x<61)=0.1356

c)p(24<x<72) =p(x<72)-p(x<24)=0.299116-0.001590.2976

d)p(x<z)=0.1 z=57.369 ==>Z=58hrs

e)p(x>m)=0.2 ==>p(x<z)=0.8 so m=99.832==>100hrs

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