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9 votes
2 answers
338 views

Probability that Mercury is the nearest planet to Earth.

Motivation: We tend to think of Venus as the nearest planet to Earth because at its nearest approach to Earth, Venus is the closest at 39 million Km away. This is followed by Mars at 56 million Km and ...
Nilotpal Sinha's user avatar
1 vote
0 answers
53 views

Distances of points in unit square to N random anchor points

Assume that N points are distributed uniformly randomly within the unit square, and call these points anchor points. What is the mean, mean minimum, and mean maximum distance of a point randomly ...
li9i's user avatar
  • 45
-1 votes
2 answers
188 views

Probability function for distance to the nearest neighbour given $n$ points distributed randomly on a line? [closed]

Note: I'm not familiar with a lot of mathematical terminology, so please excuse any misuses. I'd also make a request to use simpler language (if possible) in an answer What I'm seeking is similar to ...
acki02's user avatar
  • 101
3 votes
1 answer
809 views

If $U$ is uniformly distributed on $S^{d-1} \subset \mathbb{R}^d$, what's the distribution of its orthogonal projection onto any vector?

Let $U \in S^{d-1} \subset \mathbb{R}^d$ follow a uniform distribution on a sphere. Let $v \in \mathbb{R}^d.$ Then is the orthogonal projection $U^{T}v=\langle U,v \rangle$ uniformly distributed, and ...
Learning Math's user avatar
0 votes
1 answer
485 views

For $ x,y,z \in (0,1) $ chosen randomly with uniform distribution, what's the probability that $x+y+z<1$? [duplicate]

I tried the $2D$ case with $x,y \in (0,1)$ and $P(x+y < 1) = \frac{1}{2}$ I got this by sketching the inequalities in the question, namely $ 0\leq x,y\leq 1, $ and $y < 1-x$ and seeing that ...
Instagram-creative_math_'s user avatar
3 votes
1 answer
173 views

Density of the first $k$ coordinates of a uniform random variable

Suppose that $X$ is distributed uniformly in the $n$-sphere $\sqrt{n}\mathbf{S}^{n-1} \subset \mathbf{R}^n$. Then apparently the distribution of $(X_1, \dots, X_k)$, the first $k < n$ coordinates ...
Drew Brady's user avatar
  • 3,774
0 votes
1 answer
96 views

Probability two splits make triangle

This is a slight variation on the usual broken stick problem. A stick is broken randomly into two pieces. The larger piece is then broken in two. What is the probability the pieces can form a ...
louis's user avatar
  • 31
5 votes
1 answer
354 views

What is the probability that the larger of two independent uniform variables on $[0,1]$ is greater than $3/4$ if the smaller one is less than $1/4$?

Two independent random variables are uniformly distributed on $[0, 1]$. The question asks if the smaller of the two numbers is strictly less than $\frac{1}{4}$, then what is the probability that ...
Nishant Singh's user avatar
1 vote
2 answers
77 views

What is the expected perimeter of the quadrilateral implied by choosing points uniformly on each side of a unit square?

On each side of a square with unit length sides choose a point uniformly. Connect these points to form a quadrilateral. What is the expected perimeter of this quadrilateral? I am able to simulate ...
Goldbug's user avatar
  • 1,024
2 votes
1 answer
95 views

What is the expected length of the implied side and area formed by bending a unit length at a random point and angle?

What is the length of the length of the implied side and area of a triangle created by bending a unit length at a uniformly distributed point and angle? By simulation it seems that the expected length ...
Goldbug's user avatar
  • 1,024
6 votes
3 answers
244 views

What is the expected length of the hypotenuse formed by bending a unit length randomly at a right angle?

This is easy enough to simulate and find the answer is somewhere around .812. However I am not finding it so easy to solve the integral involved which I believe is... $$\int_0^1 \sqrt{x^2+(1-x)^2} dx$...
Goldbug's user avatar
  • 1,024
5 votes
2 answers
2k views

Average shortest distance between some random points in a box

Suppose there is a square box with side length $m$ (measured in pixels). Let there be $n$ points in this box, distributed uniformly within the box (with integer coordinates, aligned to a pixel grid). ...
Adam's user avatar
  • 51
3 votes
1 answer
626 views

Estimating number of points on convex hull constrained in a triangle

I am distributing points uniformly within an equilateral triangle: I would like to make a guess, for any given number of distributed points, how many of those points on average will be on the convex ...
Riot's user avatar
  • 135
1 vote
0 answers
291 views

Uniform Coin Drop Probability

Suppose that we drop a round coin with a diameter of 1 cm onto a gigantic sheet of paper with red lines drawn vertically every 10 cm and blue lines drawn horizontally every 5 cm. (i) What is the ...
Deegeeek's user avatar
  • 167
2 votes
1 answer
464 views

Probability that n points on a circle are in one quadrant

Question Points $A$,$B$ and $C$ are randomly chosen from a circle, What is the probability that all the points are in one quadrant ($\frac{1}{4}$ circle)? My try Using this answer about ...
user2838619's user avatar
  • 3,130

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