Section2 - Devore 5th Edition Section 3.2#12(pp 108 Let X =...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Devore 5 th Edition, Section 3.2 #12 (pp. 108) Let X = the number of tires on a randomly selected automobile that are under inflated a.) Which of the following three p ( x ) functions is a legitimate pmf for X ? Why are the other two not allowed? x 01234 p(x) 0.3 0.2 0.1 0.05 0.05 p(x) 0 . 40 . 10 . . . 3 p(x) 0 . . . 20 . . 3 Only the second p(x) satisfies the following two conditions for a legitimate pmf: 1. () 0 x p 2. 1 4 0 = = x x p b.) For the legitimate pmf of part (a), compute: P(2 X 4) = p(x) + p(3) + p(4) = 0.1 + 0.1 + 0.3 = 0.5 P( X 2) = 0.4 + 0.1 + 0.1 = 0.6 P( X 0) = 1-0.4 = 0.6 c.) Suppose: p ( x ) = c (5- x ) for x = 0, 1, …, 4 What is the value of c ? [ Hint : Σ p ( x ) = 1] = 4 0 x x p = ( ) ( ) ( ) ( ) 4 5 3 5 2 5 1 5 0 5 + + + + c c c c c = 5c + 4c + 3c + 2c + 1c = 15 c Because = 1, we have c = 1/15 = 4 0 x x p 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Counting Problems: 1. A party has 50 persons. 45 of them are boys. 5 are girls. If we select randomly 6 people, a.) What is the probability to have exactly 1 girl? Pr[Select exactly 1 girl] = () ( ) 45 5 51 50 6 0.384 = b.) To have at least 2 girls? P[Select at least 2 girls] = 1 – P[Select no girls] – P[Select exactly 1 girl] 45 5 45 5 60 50 50 66 1 0.103 =− = 2. There are 20 people at a party.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/02/2008 for the course CEE 3040 taught by Professor Stedinger during the Fall '08 term at Cornell.

Page1 / 4

Section2 - Devore 5th Edition Section 3.2#12(pp 108 Let X =...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online