My Math Forum  

Go Back   My Math Forum > College Math Forum > Advanced Statistics

Advanced Statistics Advanced Probability and Statistics Math Forum


Reply
 
LinkBack Thread Tools Display Modes
January 27th, 2011, 04:03 PM   #1
Newbie
 
Joined: Feb 2009

Posts: 21
Thanks: 0

Probability question

Question : How many times should a coin be tossed so that the probability of at least one head is >= 99%

Attempt, straight from the definition :

P(N = n) = (1-p)^(n-1) * p, where p is the probability of success

0.99 = (1-1/2)^n * 1/2

0.99 = (1/2)^n

n = 0.0145


What am I doing wrong?
tnutty is offline  
 
January 27th, 2011, 04:31 PM   #2
Global Moderator
 
CRGreathouse's Avatar
 
Joined: Nov 2006
From: UTC -5

Posts: 16,046
Thanks: 938

Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms
Re: Probability question

Quote:
Originally Posted by tnutty
What am I doing wrong?
You're calculating the probability of flipping n coins, all but the last being tails and the last being heads. It's an entirely different problem.

You should set the odds of getting all tails to 1% and solve.
CRGreathouse is offline  
Reply

  My Math Forum > College Math Forum > Advanced Statistics

Tags
probability, question



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Probability Question jskrzy Probability and Statistics 4 October 31st, 2011 02:11 PM
Probability Question skate_rds Advanced Statistics 3 March 17th, 2011 07:37 AM
Another Probability Question skate_rds Advanced Statistics 0 February 6th, 2011 09:16 PM
Probability question madflame991 Probability and Statistics 0 February 1st, 2011 01:06 AM
At Least One - Probability Question edouble2k6 Advanced Statistics 5 October 22nd, 2007 10:31 AM





Copyright © 2019 My Math Forum. All rights reserved.