This preview shows pages 1–4. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: STA 103 Exam 2a Fall 2007 I. H. Dinwoodie NAME Calculator allowed, closed book. STA103 Fall 2007 E2a 1 Circle True or False. (1 point each) 1. The population of American men in 1975 had incomes that averaged , with variance 2 . A random sample of 1000 men was drawn to estimate and 2 . (a) T The probability histogram of the sample should resemble the prob ability histogram of the population. (b) F The sample mean is a biased estimator of . (c) F The sample variance is a biased estimator of 2 . (E( S 2 ) = 2 ) (d) F The probability distribution of the sample mean X has a density that resembles the probability histogram of the population. (e) F The variance of the sample mean is the same as the variance of the population. (Var( X ) = 2 / 1000) (f) F A 95% confidence interval for is wider than a 99% confidence interval for . (g) F A 99% confidence interval for will always contain the mean . (h) F The mean squared error (MSE) of the sample mean for estimating is 2 . (MSE( X ) = 2 / 1000) (i) F The mean squared error (MSE) of the sample mean for estimating is greater than the MSE of a single draw. (j) T The sample mean has a probability distribution that is bellshaped and is more tightly concentrated around than the distribution of the population. (Central Limit and the MSE of X apply) STA103 Fall 2007 E2a 2 2. (4 points) In a large American university in 1969, 3 men and 4 women profes sors were sampled independently, yielding the annual salaries given below (in thousands): Women Men 8 13 10 12 16 23 15 (a) Construct a 95% confidence interval for the difference of the mean salaries...
View
Full
Document
This note was uploaded on 09/29/2008 for the course STAT 103 taught by Professor Dinwoodie during the Fall '08 term at Duke.
 Fall '08
 Dinwoodie
 Statistics, Probability, Variance

Click to edit the document details