This preview shows pages 1–2. Sign up to view the full content.
Solutions to Homework #2
(W4150 ‘Intro to Probability and Statistics’, S04)
Sec. 2.5. (8)
Let A = {there is a defect in braking system} and B = {there is a defect in fueling system}.
We are given that P(A) = .25, P(B) = .17 and P(A
B) = .15. Then:
(a) P(A
B) = P(A) + P(B)  P(A
B) = .25 + .17  .15 = .27
(b) P (No defect) = 1 – P(A
B) = 1  .27 = .73
Sec. 2.5. (12)
(a) The total number of books on the shelf is 9
there are N = C
9
3
= 84 ways to pick 3
books. Furthermore, there is just one way to pick a dictionary (so n
1
=1) and C
8
2
= 28 = n
2
ways to pick two other books out of remaining 8. Hence, by multiplicative rule n =
n
1*
n
2
and P(*) = n/N = 28/84 = 1/3
(b) By the same reasoning P(**) = C
5
2
*C
3
1
/ C
9
3
= 5/14
Sec. 2.7. (1)
(a) The probability that a convict who pushed dope, also committed armed robbery;
(b) The probability that a convict who committed armed robbery, also pushed dope;
(c) The probability that a convict who didn’t push dope, also didn’t commit armed robbery;
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
This note was uploaded on 06/02/2010 for the course IEOR SIEO W4150 taught by Professor Gallego during the Spring '04 term at Columbia.
 Spring '04
 GALLEGO

Click to edit the document details