1. The scores of individual students on the American College Testing (ACT) Program composite college entrance examination have a normal distribution with mean 18.6 and standard deviation 6.0. At Northside High, 36 seniors take the test. If the scores at this school have the same distribution as national scores, the sampling distribution of the average (sample mean) score for the 36 students is
A. approximately Normal, but the approximation is poor.
B. approximately Normal, and the approximation is good.
C. exactly Normal.
2. Suppose that you are a student worker in the Statistics Department and agree to be paid by the Random Pay system. Each week the Chair flips a coin. If the coin comes up heads, your pay for the week is $80; if it comes up tails, your pay for the week is $40. You work for the department for 100 weeks (at which point you have learned enough probability to know the system is not to your advantage). Suppose x' is your average pay for the 100 weeks. Then x' has approximately a
A. N (60, 10.95) distribution.
B. N (60, 2) distribution.
C. N (120, 20) distribution.
3. The SAT scores of entering freshmen at University X have a N (1200, 90) distribution and the SAT scores of entering freshmen at University Y have a N (1215,110) distribution. A random sample of 100 freshmen is sampled from each University, with x' the sample mean of the 100 scores from University X and the sample mean of the 100 scores from University Y. The probability that x' is greater than µY, the population mean for University Y, is
A. 0.0475.
B. 0.0869.
C. 0.4325.