All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Probability
Cars on the road (Posted on 2004-04-09) Difficulty: 2 of 5
If the probability of observing a car (read: at least one car) in 20 minutes on a highway is 609/625, what is the probability of observing a car (read: at least one) in 5 minutes (assuming constant default probability)?

  Submitted by SilverKnight    
Rating: 2.5000 (4 votes)
Solution: (Hide)
If the probability of seeing a car is 609/625, then the probability of NOT seeing a car is 1 - 609/625 = 16/625.

This means that if we must not have seen a car in each of FOUR five minute periods. So we must multiply the likelihood of NOT seeing a car in each five minutes, x (4 times) and get 16/625.

x^4 = 16/625
x = 2/5

Since the question asked about the likelihood of SEEING a car in 5 minutes, we must subtract that likelihood from 1...

1 - 2/5 = 3/5, the answer.
___________________________

Problem found at:
http://www.techinterview.org/Puzzles/carsontheroad.html

Comments: ( You must be logged in to post comments.)
  Subject Author Date
SolutionSolution To The ProblemK Sengupta2007-04-17 11:35:26
Solutionpuzzle solutionK Sengupta2007-04-17 11:29:00
hmmofnoconcern2004-11-28 15:19:55
Alternative to PoissonCharlie2004-04-10 14:17:42
re(6): One Mean Poisson = SharkPenny2004-04-09 21:53:52
re(5): One Mean Poisson = SharkRichard2004-04-09 21:35:36
re(4): One Mean Poisson = SharkPenny2004-04-09 21:19:04
re(3): One Mean Poisson = SharkRichard2004-04-09 21:13:53
re(2): One Mean Poisson = SharkPenny2004-04-09 19:28:46
re: One Mean Poisson = SharkLarry2004-04-09 19:16:04
One man's Mean is another man's PoissonPenny2004-04-09 16:01:24
SolutionSolutionRajat2004-04-09 15:37:15
re(4): Auto-suggestionThoughtProvoker2004-04-09 15:31:28
re(3): Auto-suggestionCharlie2004-04-09 14:50:43
re(3): Auto-suggestionRichard2004-04-09 14:28:47
re(2): Auto-suggestionThoughtProvoker2004-04-09 13:43:53
re: Auto-suggestionCharlie2004-04-09 13:38:18
SolutionJer2004-04-09 12:13:22
SolutionAuto-suggestionPenny2004-04-09 12:01:02
answerAdy TZIDON2004-04-09 11:17:28
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (1)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2017 by Animus Pactum Consulting. All rights reserved. Privacy Information