1143 SAQ The scores of 12thgrade students on the National As

(11.43 S-AQ) The scores of 12th-grade students on the National Assessment of Educational Progress year 2000 mathematics test have a distribution that is approximately Normal with mean ? = 280 and standard deviation ? = 34. A. Choose one 12th-grader at random. What is the probability ( 0.0001) ____ 0.1) ____ Higher than 348? (x -values? D. What is the probability that the mean score for your SRS is higher than 280? ( 0.1) of all the x -values? C. What would be the standard deviation (x . If you did this many times, what would be the mean of all the 0.001)? ____ B. Now choose an SRS of 4 twelfth-graders and calculate their mean score 0.1) that his or her score is higher than 280? ___ Higher than 348 (

Solution

mu = 280 and sigma = 34

a) P(X>348) =P(X>2) = 0.0228

D) P(x bar>280) = P(Z>0) = 0.50

B) For sample size = 4, mean remains the same 280

Hence P(X bar>280) = P(Z>0) = 0.50