The sum of several numbers divided by their count nicely summarizes the overall size of the numbers involved in a single value.
22
votes
11answers
4k views
Prove that if two miles are run in 7:59 then one mile MUST be run under 4:00.
I'm in an argument with someone who claims that a two mile in 7:59 does not imply that one mile (at some point within the two miles) was covered in under 4:00. This is obviously wrong, but I'm not ...
5
votes
4answers
753 views
How can I calculate “most popular” more accurately?
I'm developing a website at the moment.
The website allows users to "rate" a post from 0 to 5.
Posts can then be displayed in order of popularity.
At the moment, my method of calculation is pretty ...
3
votes
1answer
2k views
5 star ratings. Bayesian or Weighted average?
I am building a website which has 5 star ratings to rate items.
These ratings unlike the normal ones are of unequal weights. i.e.
...
1
vote
2answers
65 views
Calculating new vector positions
I'm using the following formula to calculate the new vector positions for each point selected, I loop through each point selected and get the $(X_i,Y_i,Z_i)$ values, I also get the center values of ...
0
votes
5answers
268 views
Is this a weighted average/percentage problem?
Let's say a Marketing company has a total turnover of 10000 \$
There are 3 salesmen A,B,C with the following turnovers
A = 2000 $
B = 3000 $
C = 5000 $
Now, ...
4
votes
1answer
204 views
Regular average calculated accumulatively
is it possible to calculate the regular average of a sequence of numbers when i dont know everything of the sequence, but just everytime i get a new number i know the total count of numbers and the ...
7
votes
3answers
244 views
Asymptotic difference between a function and its binomial average
The origin of this question is the identity
$$\sum_{k=0}^n \binom{n}{k} H_k = 2^n \left(H_n - \sum_{k=1}^n \frac{1}{k 2^k}\right),$$
where $H_n$ is the $n$th harmonic number.
Dividing by $2^n$, we ...
2
votes
2answers
330 views
What is the average of rolling two dice and only taking the value of the higher dice roll?
What is the average result of rolling two dice, and only taking the value of the higher dice roll?
To make sure the situation I am asking about is clear, here is an example:
I roll two dice and one ...
6
votes
4answers
100 views
Is there a way to get an average that weights each item inversely based on distance from the mean?
I'm not sure how to phrase this, or even if such a thing exists. Sorry!
I have a bunch of data points, which are mostly pretty tight. Each group should hone in on a specific point in space. ...
3
votes
1answer
206 views
Average sine of an angle between two rays in a cone
I'm looking for an average value of sine of an angle between two rays, lying within a cone with a certain angle.
Given a cone with an aperture of ${2\chi}$ and two rays lying within the cone. The ...
3
votes
4answers
174 views
If $\sum\limits_{k=1}^n y_k\geq n$ and $\sum\limits_{k=1}^n \frac{1}{y_k}\geq n$, then $\prod\limits_{k=1}^n y_k\geq 1$?
Let $y_1,\ldots y_n$ be positive real numbers satisfying
$y_1+\cdots+y_n\geq n$ and $\displaystyle{\frac{1}{y_1}+\cdots+\frac{1}{y_n}\geq n}$.
Is it true that $y_1y_2\cdots y_n\geq 1$?
2
votes
1answer
91 views
Average number of rolls of die to see each side at least once [duplicate]
Possible Duplicate:
A Question About Dice
You have a weighted n-sided die. Every side of the die is weighted differently where side n1 has a weight of w1, n2 has a weight of w2, ...
...
2
votes
1answer
156 views
Remove statistical outliers
I've analysed newspapers by counting the language distributions of the articles.
The results look like that:
...
1
vote
1answer
85 views
Fréchet mean between points in $\mathbb{R}^3$
Let $X$ be a set of $n$ points in $\mathbb{R}^3$ and $f_m$ be the Fréchet mean, i.e.:
$$
f_m= \arg \min_{p \in M} \sum_{i=1}^n w_id^2(p,x_i)
$$
where $(\mathbb{R}^3,d)$ is a complete metric space, ...
-1
votes
1answer
887 views
Can weighted average be used to calculate percentage increase? [duplicate]
Possible Duplicate:
Is this a weighted average/percentage problem?
Let's say a Marketing company has a total turnover of 10000 \$
There are 3 salesmen A,B,C with the following turnovers:
...
