Homework 3, Econ 400

Homework 3, Econ 400 - Economics 70 Answer key to Book...

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

View Full Document Right Arrow Icon
Economics 70 Answer key to Book Problem 3 Exercise Title: Book Problem 3 Date: 5/12/2009 Name (Last, First): ANSWER KEY PID: Sign the Honor Pledge: 3.17 a) The probability that a person is a college graduate, P(A), is 0.24. The probability that a college graduate believes the ad, P(B|A), is 0.18, so the probability that a college grad does not believe the ad, P( B |A ), is 1 – 0.18 = 0.82. Thus, the P( B | A)P(A) = (0.82)*(0.24) = 0.197 b) The probability that an adult with some college believes the ad is 0.25, so the probability that an adult with some college does not believe the ad is 1 – 0.25 = 0.75 c) The probability that an adult has not been to college, P(C), is 0.4. The probability that someone who has not been to college believes the ad, P(D), is 0.27. The joint probability, P(CD) = P(D | C)P(C) = (0.27)*(0.4) = 0.108 3.19 Define the following events: A: car has been in an accident in the past year B: car has anti-lock brakes a) P(A) = P(AB) + P(A B ) = 0.03 + 0.12 = 0.15 b) P(ĀB) = 0.40 c) P(B | A) = P(AB) = 0.03/0.15 = 0.2 P(A) 3.21 Define the event A: executive will use the information superhighway. a) P(A) = 0.40 b) If two executives are randomly chosen, a simple event consists of a pair, the first element representing the first executive’s action, and the second representing the action of the second executive. Then the event that only one of the two executives will use the Information Superhighway is composed of two simple events, AĀ and ĀA. The probability is P(AĀ) + P(ĀA) = (0.4)*(0.6) + (0.6)*(0.4) = 0.48 3.23 Define the following events: A: Device A is activated B: Device B is activated It is given that P(A) = 0.91 and P(B) = 0.95, and that the two systems (and hence, events A and B) are independent. Then P(system functions) = P(either or both device activates) 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
= P(A B) = P(A) + P(B) – P(AB) = P(A) + P(B) – P(A)P(B) = 0.91 + 0.95 – (0.91)*(0.95) = 0.9955 3.25 The denominator given in the formula for P(s i | I ) is 3 . ) 2 (. 5 . ) 3 (. 2 . ) 4 (. 2 . ) 1 (. 6 . ) | ( ) ( ) ( 4 1 = + + + = = = i
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.

Page1 / 6

Homework 3, Econ 400 - Economics 70 Answer key to Book...

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