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Browse College Probability
Stars indicate particularly interesting answers or
good places to begin browsing.
See also College Statistics.
 Probability of at Least 45 Heads in 100 Tosses of Fair Coin [05/15/2004]

What is the probability of getting at least 45 heads out of 100
tosses of a fair coin? I have two different answers and I'm wondering
which, if either, is correct.
 Probability of Continuous Random Variables [04/23/2003]

My book says that for any continuous random variable X, P (X=x)=0.
Using calculus, I can figure out the probability is 0, but by
intuition, I can't see why.
 Probability of Duplicate Pairs [05/13/2003]

Find the probability of getting at least 20 duplicate addresses when
drawing a sample of 30,000 at random from UK households (estimate
21,000,000) where there is replacement every time a selection is made.
 Probability of Forming a Triangle [01/24/2001]

A rope one unit long is cut in two places. What is the probability that
the three resulting pieces can be arranged to form a triangle?
 Probability of Multiple Failures [06/20/2002]

If two components have average lifespans of 2500 hours, and the
probability of failure for each is f(t) = (1/u)e^(t/u), what is the
probability (1) that both components will fail within 2500 hours, and
(2) that both will fail within a total of 2500 hours of operating
time?
 Probability of Never Having a Losing Record [04/07/2001]

Suppose a football team plays 8 games, and the chance of winning any
particular game is 50%. What is the probability of completing the season
without more losses than wins?
 Probability of Repeating Digits [11/8/1994]

A native speaker of German writes: The decimal representation of a real
[number] can be viewed as pseudorandom because it's not ending and not
repeating. If you take any real, what is the probability of finding
987987987 in the decimals?
 Probability of Typing a Sonnet [9/2/1996]

Statistics, God, and the probability of life arising by "pure chance"...
 Probability of Void Hand in Card Game of Bridge [12/02/2004]

What is the probability of being dealt a bridge hand void in a
specified suit from an ordinary deck of 52 playing cards?
 Probability Philosophy and Applying Inference [10/11/2004]

If I flip a coin 4 times and they all turn out to be heads, what is
the probability that the coin is fair?
 Probability That Random Chord Exceeds Radius in a Circle [11/20/2004]

If a chord is selected at random on a fixed circle, what is the
probability that its length exceeds the radius of the circle?
 Probability That Someone Shares Your Birthday [05/14/2002]

How many people would you have to share a room with before the
probability that one of them shares your birthday is at least 50%?
 Probability Using Geometric Random Variables [01/15/2004]

Let X be a geometric random variable with parameter p1 and let Y be a
geometric random variable with parameter p2. Find the probability
that X is less than or equal to Y.
 Probability with a Weighted Coin [04/12/2001]

Find the probability of getting three heads in a row with a weighted
coin, with a 1/3 probability of getting a head on each toss. What if I
want to be 99% sure of getting three heads?
 PValue Calculation [04/12/1997]

I am able to determine the chisquare value, but I do not know how to
determine the pvalue, or if I can even do that.
 Question on Probability of Repeating Digits [04/18/2001]

You said that the probability is 1 that you can find any number with that
string in it. I don't understand how.
 Random Card Shuffling Probabilities [6/11/1996]

What is the probability of at least two eights being next to each other
in a random shuffling of a deck of cards. What about at least two cards
(2 eights or 2 queens etc.) being next to each other?
 Randomly Cutting a Rope into Two Segments [05/14/1998]

A rope 20m long is randomly cut into two segments, each of which is used
to form the perimeter of a square . . .
 Random Variables and Order Statistics [08/16/2001]

Let X1, X2, ....., Xn be n independent and continuous random variables
with the same distribution, let X denote the maximum and Y the minimum of
these random variables, and let U = X / Y; find the distribution of X,Y,
and U.
 Random Walk Coin Simulation [10/27/2005]

A game starts with a score of zero, and adds or subtracts one based on
whether coin flips come up heads or tails. Is there a way to calculate
how many coin tosses it will take to reach a score of n or n?
 Random Walk Problem [04/10/2006]

What is the probability that Dorothy doesn't fall off the cliff if she
starts one step away from it and moves backwards and forwards one step
at a time depending on the toss of a coin?
 Regression Analysis of FourParameter Data [01/21/2000]

How do I perform a regression analysis on fourparameter experimental
data to determine the values of A, B, C and D in the equation y = [(A
D)/(1+{x/C}^B)]+D?
 Riemann, Mayan Math [5/20/1996]

Math projects: A. Riemann  a German mathmatician; B. The Mayan number
system and calendar; C. Probability.
 Rolling Dice and Probability [11/07/2007]

If I roll a die 10 times, what is the probability that I will have
gotten all numbers from 1 to 6 at least one time each?
 Runners and Heart Attacks [01/14/1997]

Given data regarding the occurrence of heart attack among runners and
nonrunners, determine whether there is a connection between runner
status and heart attacks.
 Running Shoes [02/07/2001]

What proportion of the time does the runner run barefoot?
 Sharing a Zodiac Sign [04/24/2001]

In a class of 35 students, what is the probability that every student in
the class will have the same zodiac sign as at least one other classmate?
 Social Security Number Probability [02/09/2004]

What are the chances that a 9digit Social Security number is
comprised entirely of 2 digits, such as 211121221?
 Stochastic Matrices [03/17/1998]

Finding the transtion matrix and steadystate vector of a stochastic
process.
 Stocks and the Binomial Distribution [12/09/1998]

If an index of stock prices has probability 0.65 of increasing in any
year, how can you turn this into a binomial distribution question?
 Sum of 5 or 7: Dice Probability [09/11/2002]

A pair of dice is rolled until a sum of either 5 or 7 appears. Find
the probability that a 5 will occur first.
 Sum of Two Arcs [01/30/2003]

Three points are taken at random on the circumference of a circle.
What is the chance that the sum of any two arcs so determined is
greater than the third?
 Ten Coin Flips, Four Heads [05/08/2001]

If you flip a coin ten times, what is the probability of getting at least
four heads?
 Theory of 'Runs' [8/20/1996]

If all possible orders of 20 people are considered, what is the average
value of the number of places in the row...?
 Three Pieces of a Stick Forming a Triangle [01/22/2007]

If you break a straight stick into three pieces, what is the
probability that you can join the pieces endtoend to form a triangle?
 A Triangle in a Circle [05/26/2000]

Suppose you randomly place 2 points on the circumference of a circle.
What is the probability that a 3rd point placed randomly on the circle's
circumference will form a triangle that will contain the center of the
circle?
 The Two Envelope Paradox in Probability and Expected Return [09/20/2005]

A classic problem in which two envelopes contain money, one double the
other. After choosing one at random, should you trade it for the
other? It appears there should be no advantage, but the expected
values suggest otherwise. Or do they?
 TwoHeaded Coin and Bayesian Probability [04/21/2003]

In a box there are nine fair coins and one twoheaded coin. One coin
is chosen at random and tossed twice. Given that heads show both
times, what is the probability that the coin is the twoheaded one?
What if it comes up heads for three tosses in a row?
 Two Random Variables, Each Correlated to a Third [04/29/2003]

If X, Y, and Z are 3 random variables such that X and Y are 90%
correlated, and Y and Z are 80% correlated, what is the minimum
correlation that X and Z can have?
 Uniform and Exponential Distribution of Random Variables [01/16/2006]

Can you prove that if you take the natural log of a uniformly
distributed random variable, it becomes a exponentially distributed
random variable?
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