The director of admissions at the University of Maryland, University College is
ID: 3174831 • Letter: T
Question
The director of admissions at the University of Maryland, University College is concerned about the high cost of textbooks for the students each semester. A sample of 25 students enrolled in the university indicates that x(bar) = $515.40 and s = $43.20. Using the .10 level of significance, is there evidence that the population mean is above $300? No, because 500 is below the lower limit of the confidence interval Yes, because 300 is below the lower limit of the confidence interval No, because 300 is in the confidence interval Yes, because 300 is in the confidence IntervalExplanation / Answer
right choice is second. Yes, because 300 is below the lower limit of the confidence interval
here n=25, sample mean=315.4,sd=43.2
(1-alpha)*100% confidence interval for mean=mean± z(alpha/2)*sd/sqrt(n)
90% confidence interval for mean=mean±z(0.1/2)*sd/sqrt(n)=315.4±1.645*43.2/sqrt(25)=315.4±14.2=
=(301.2,329.6)
since 300 is out of the interval , so we can say that there is evidence of population mean is above 300.