This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: Spring 2012 STAT 512 HW 0A 1 Homework 0A (Review?) due Jan. 13 The following problem set is based from information in Appendix A. This is review or new material depending on which statistics course you took as a prerequisite. 1. (From A.3) A certain automobile manufacturer equips a particular model with either a six cylinder engine or a fourcylinder engine. Let X 1 and X 2 be fuel efficient for independently and randomly selected sixcylinder and fourcylinder cars, respectively. The means and standard deviations are as follows: E{X 1 } = 22 {X 1 } = 1.2 E{X 2 } = 26 {X 2 } = 1.5 a) Calculate the mean and standard deviation of D = X 1 X 2 . E{D} = E{X 1 } E{X 2 } = 22 26 = 4 ? = 2 1 + 2 2 = 1.2 2 + 1.5 2 = 1.921 b) Calculate the mean and standard deviation of T = X 1 + X 2 . E{T} = E{X 1 } + E{X 2 } = 22 + 26 = 48 = 2 1 + 2 2 = 1.2 2 + 1.5 2 = 1.921 = ? c) Calculate the mean and standard deviation of A = T/2. ? = ? { } 2 = 48 2 = 24 = 2 = 1.921 2 = 0.960 2. (A.4) Suppose the tensile strength of typeA steel has a distribution of N( = 105 ksi, 2 = 64 ksi 2 ) and the tensile strength of typeB steel has a distribution of N( = 100 ksi, 2 = 36 ksi 2 ). Assume that the strengths of the two types of steel are independent. Let T = A + B....
View Full
Document
 Spring '08
 Staff
 Statistics

Click to edit the document details