The sum of several numbers divided by their count nicely summarizes the overall size of the numbers involved in a single value.

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0
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2answers
24 views

Volume and Average Height

How do you calculate the average number of floors of buildings across a city block when all the buildings are varying heights. Followings in a listing of what the area looks like and the number of ...
3
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3answers
3k views

what does `ensemble average` mean?

I'm studying this paper and somewhere in the conclusion part is written: "Since this rotation of the coherency matrix is carried out based on the ensemble average of polarimetric scattering ...
0
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0answers
35 views

How can I calculate accuracy of an estimate based on a subset of data?

For example, say I'm trying to determine the average number of steps taken in a day for a population of 100M people. I know the exact number of steps for a random 25M subset of the 100M group (2500 ...
-1
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1answer
17 views

How can I get the average angle from a set of three points?

Please forgive me, but I'm not mathematically inclined and i'm trying to solve a problem for a video game i'm developing. My levels are composed of vector shapes and i want to find out what the ...
0
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0answers
9 views

Normalize and Average weighted

Everyday I receive a data of three variables (neutral, negative and positive). ...
0
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0answers
19 views

Boosting v. weighted average

I have been watching an MIT online Artificial Intelligence lecture by Prof. Winston about boosting. The boosting technique uses complicated maths to combine the results from several weak predictors to ...
14
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3answers
395 views

If my average speed is 50 mph, is it better to go 10% faster or 5 mph faster? (These are not the same)

BACKGROUND Suppose we have a journey between $A$ and $B$ where different sections of roads have different speed limits and our average speed is $50$ mph. If when I repeat the journey I travel $10\%$ ...
0
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0answers
7 views

Calculate popularity (frequency) of an item sold from multidimensional array [closed]

I have an array extracted from my database online where i store id status: sold / not sold time: day that the item sold or not price sold and the output example is given below ...
1
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0answers
38 views

What is the average maximum value of a set of random numbers? [duplicate]

Let $a_1, a_2, a_3, \ldots, a_{10}$ be ten randomly chosen real numbers in the interval [0,1]. Let $m$ be the maximal value out of these 10 numbers. What is the expected value of $m$? (i.e. If i ...
0
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0answers
25 views

Anyone have any good ideas on how to average 2D directions?

Directions, being a cyclical quantity (i.e. if you keep increasing the value, you'll eventually end up back where you started) can't be averaged out like regular numbers. For example, say I have 2 ...
0
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0answers
17 views

The average value of f on region R (double integrals)

If I am given f(x,y) and I calculate the average of the region given by the formula in this image should the average always = (min of f(x,y) +max of f(x,y))/2. I think this is only the case if the ...
0
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0answers
33 views

How can I calculate my current average for my class?

I'm trying to do some what-if scenarios for one of my courses and I'd like someone to double check my work. The grade breakdown is as follows: ...
0
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2answers
44 views

How do I calculate a combined data error?

I have a time series of data points read from an instrument, I also get an estimate of the error ($\sigma$) for each of these readings. e.g. $10.12 \pm 0.05$ $10.09 \pm 0.02$ $10.20 \pm 0.12$ ...
-1
votes
1answer
16 views

Buying forecast

I have a set of items. In 2013, I bought x of a certain item, in 2014 I bought y, and in 2015 I bought z. In many cases, I only bought the item in one year, like: ...
0
votes
1answer
55 views

What is the name of this formula??

Let formula_a = lambda array: sum(array) / len(array). We may rename this formula to be average or ...
1
vote
1answer
15 views

How is the first term weighted in an exponential smoothing, or exponentially weighted moving average?

I'm working with exponential smoothing for a series, using the formula $z_i=\lambda \bar x_i + (1- \lambda) z_{i-1}$, as explained in this wiki article. Using this method, should $z_{1}$ be defined ...
0
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0answers
17 views

How do you set the half-life of an exponential weight?

I'm trying to follow the process described in a paper, where they smooth a time series using exponential weights, for which I'm using the formula $z_i=\lambda \bar x_i + (1- \lambda) z_{i-1}$, as ...
2
votes
3answers
1k views

find new average if removing one element from current average

Ok, so say that I have a current rating average: 3.3/5 Now I want to say to remove a rating of 4. How do I find the new average? Or is this even possible?
1
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0answers
17 views

Confused by simple risk problem

I am having troubles understanding this basic problem and would like to see if anyone could help me out. I have two boxes: one red, one blue. Depending on what box I pick, I have the potential to ...
0
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2answers
41 views

Bit increase when averaging?

I have a given number $N$ of binary numbers, that are stored using a given number $B$ of bits. $B$ is the same for all the numbers. For example, thease values where $N = 4, B = 4$. ...
0
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0answers
16 views

Can distributions scale to any given time scale?

I am working with some colleagues to set up alerts based on call center data, and I feel that something is wrong with how it is currently being done, but I'm not sure what exactly, or how to explain ...
0
votes
1answer
24 views

Applications of mean and standard deviation

If I have this set of numbers: [9,7,5,5,4,4,4,2] We know that: mean = 5 variance = 4 standard deviation = 2 But is there an application/formula of standard ...
43
votes
3answers
69k views

Why is an average of an average usually incorrect?

Can someone explain why taking an average of an average usually results in a wrong answer? Is there ever a case where the average of the average can be used correctly? As an example, let's say ...
0
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1answer
19 views

The average of 38,84,63,45,32 and n lies between 50 and 60.If n is an integer greater than the average of the above numbers, then n lies between?

The options are 53 < n <97 50 < n < 100 52 < n < 98 I added the values along with n to get 43.66 + n/6.I then tried plugging in values from the options and tried arriving at ...
0
votes
2answers
39 views

A worker is told that only $5\%$ of all workers make a higher wage. If the wages are normally distributed, what is the average hourly wage?

So let's say a worker earns $\$16$ per hour at a plant and is told that only $5\%$ of all workers make a higher wage. If the wages are normally distributed with standard deviation of $\$5$ per hour ...
0
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0answers
16 views

How to determine a formula for an index of compliancy

I hope you will be patient with the inarticulate question of a non-mathematician. It's hard to get an answer when you don't even know how to ask the question. Here the contest: Let's say that I have ...
1
vote
1answer
397 views

Calculating average customer turnover

I am currently coding a script which displays data for a company intranet. I am stuck with a question that seemed pretty simple, but turned out to give me headaches. We have the following scenario: ...
0
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2answers
33 views

Average time between successive occurrences of earthquakes?

In any given year, the probability of an earthquake greater than Magnitude $6$ occurring in the Garhwal Himalayas is $0.04$. The average time between successive occurrences of such earthquakes is ____ ...
1
vote
0answers
15 views

Average Value of a Line Integral

I'm having quite a hard time calculating the average value of a line integral. Given the surface $f(x,y) = \sqrt{16 + 36y^{2/3}}$ and the curve $y = x^{3/2}$, I need to calculate the average value of ...
0
votes
1answer
35 views

Average cost of units over time

I buy and sell units at varying price and I always have a varying stock of units bought in different batches at different prices. I always keep the current_price and the current_volume and I base my ...
6
votes
7answers
46k views

Sum of averages vs average of sums

I have essentially a table of numbers -- a time series of measurements. Each row in the table has 5 values for the 5 different categories, and a sum row for the total of all categories. If I take ...
0
votes
0answers
8 views

Average discount give for product line

I have been out of school for entirely too long to remember how to build this equation. I am trying to calculate the average discount given for our entire product line, that is sold over 4 distinct ...
2
votes
3answers
2k views

Way to aggregated percentiles

I want to have information of http response times. The average, 95 and 99 percentil. All the response times are collected in each web server, and every second is sent back to a central server that ...
0
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1answer
33 views

Function to determine a set of numbers are balanced

Given the following data, based on a 0-100 scale ...
2
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2answers
35 views

Is there a name for the way I am averaging the cost of cards?

My buddy and I were discussing different ways of deciding how much mana to include when constructing a deck. Without thinking much about it I used a method of finding the average converted mana cost ...
2
votes
3answers
57 views

Determining the Average number of Attempts before a result occurs (using defined Probabilities)

I'm trying to solve this problem but I'm completely unsure of what sort of concepts/formulas/proofs I need in order to tackle it. I'm just lost on where to start. Here's an example story problem as it ...
1
vote
1answer
28 views

Weighted average of multiple weighted factors

Lets say a factory machine runs as follows: Day 1: $3$ widgets per minute $\times 1000$ minutes $\times 1$ kg per widget $= 3000$ kg. Day 2: $5$ widgets per minute $\times 800$ minutes $\times 1.5$ ...
1
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2answers
23 views

Reporting numbers that vary

I'm timing how long various parts of a computer program takes to run, with the intent of including this in a research paper. There are fluctuations in the timing based on the usual things inside a ...
0
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0answers
20 views

What is the appropriate way to average a set of slopes?

I have a set of line slopes (output from linear regressions) and I'd like to combine them to yield some measure of the 'slope' of the set. However, simply taking the mean of the numbers doesn't make ...
2
votes
2answers
75 views

How do I find the average of top list items? [closed]

Here's the situation: I have a lot of "top lists" like so: list1: iPhone 6 Galaxy S5 LG G4 list2: Galaxy S5 OnePlus One iPhone 6 LG G4 Nexus 5 list3: LG G4 Galaxy S5 Nexus 5 And so on... ...
0
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0answers
8 views

Another name for mode frequency

Is there another term for the number of times the mode number occurs in a list/array of numbers or 'the frequency of the mode' in a list/array of numbers? Apologies if this has been asked before - I ...
1
vote
1answer
23 views

Looking for an equation that reflects the majority of a collection

I'm working on a computer program, part of which involves sifting through large collections of numbers (by large, I mean 16 million+ numbers). I expect these collections to almost entirely be composed ...
1
vote
1answer
16 views

Averaging several factor of multiplication function

So, I have these kind of equations: $k_{A_1}*k_{B_1}*k_{C_1} = f_1$ $k_{A_2}*k_{B_2}*k_{C_2} = f_2$ ... $k_{A_7}*k_{B_7}*k_{C_7} = f_7$ What I have is $f_1$,$f_2$,...$f_7$ Is there any way to get ...
3
votes
3answers
54 views

Why this statistical equation is true?

Pardon my ignorance. I also don't know how to properly show the equation. So I attached URL of latex... Why this equation is true for any real number $k$, when $\overline{X}$ is average of individual ...
0
votes
1answer
36 views

Integrated average value of a multivariate function doesn't match average obtained through simulation.

So, recently I have been trying to calculate the expected area of a convex cyclic quadrilateral with perimeter $1$. Nonetheless, I will only post what's relevant to the issue - the fact that the ...
0
votes
2answers
50 views

The average age of 30 boys in a class is 16, including the teacher it is 17. What is the teacher's age?

The average age of $30$ boys in a class is $16$. If the teachers is included the average increases by $1$. What is the teacher's age? Options: $37$ yrs $30$ yrs $47$ yrs $57$ yrs None of these ...
0
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0answers
9 views

Weighted Average Using Rankings

So I have this data and I've ranked each category for each person. The best being 1. I can average them , just add up and divide, but I need to weigh them. If I weigh them like normal: ...
6
votes
3answers
15k views

what is the difference between average and expected value?

I have been going through the definition of expected value in Wikipedia (http://en.wikipedia.org/wiki/Expected_value) beneath all that jargon it seems that the expected value of a distribution is the ...
1
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0answers
26 views

Expected waiting time - simplified

I need some assistance with a calculation I'm trying to do. I have access to surgery waiting times data (date arrived, date completed) and I want to figure out the expected waiting time for a new ...
0
votes
2answers
23 views

Mean value of positive numbers in an arbitrary set of numbers

I have a set with an arbitrary amount of positive and negative numbers. Now I want to calculate the mean value of all numbers inside the set which are greater than $0$. Is there a mathematical way of ...