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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37 views

Approximate simple moving average knowing only previous SMA?

I know it's possible to calculate a regular average incrementally knowing the previous average, the next number and the number of items. But is this possible for a moving average of N items, at least ...
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1answer
71 views

Calculate a Ranking Average

I got stuck to find a fair formula to calculate the average ranking of the itens that I found after consecutive searches, look: If I calculate the simple average of the item2 for example I get 1,33 ...
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1answer
21 views

Which average to use with range

Say I wanted to calculate how much rain in terms of volume falls on the Earth each day or hour, etc. In order to do so I'd first need to know how much water is in a single raindrop. I know that and it ...
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1answer
50 views

Why must average only be used with normal distribution?

In a technical job interview I was asked a question that I couldn't quite make sense of. The interviewer was talking about sampling a sound file to make a visual effect (such as a graph that moved to ...
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1answer
23 views

A Basic Math Question on Averages

Okay this is going to sound really stupid but I'll ask anyway... I need to get a $5.5$ accumulative GPA (the highest is a $7.0$). For the last $16$ classes I've done my GPA is sitting at $5.44$. I'm ...
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1answer
48 views

Running a Cumulative Average

I'd like to run a cumulative average and I'm wondering if my process is sound. Here's a small dataset: Row 1: $\frac{2\cdot 60}{58} = 2.07$ Row 2: $\frac{4\cdot 45}{44} = 4.09$, ...
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1answer
43 views

What kind of a mean value is this?

I wasn't that sure what kind of mean value the following is, I hope you can help me out: What it's about: I have this testseries of about 30 elements, that delay the boot sequence of an embedded ...
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1answer
79 views

Catastrophic Cancellation

I need some informations about algorithms to solve the problem of Catastrophic Cancellation, or in general to calculate mean and variance of a data stream. For example about Donald Knuth's algorithm ...
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2answers
56 views

Get N values between 0 and 1 AND control spacing of results.

So I need to get N number of values between 0 and 1. The values should be evenly spaced. Thats easy... However, I also want another variable X that will shift the resulting values closer to 0 or 1. ...
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1answer
114 views

Most accurate mean for grouped/ranged data

I've got data in a range and frequency format e.g 0-5 : 3, 6-10 : 70 etc up to 31-35. How do I get the most accurate mean for such data?
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0answers
31 views

Getting the average of a serie of values

I am trying to smooth out a serie of values that represents tempo values, depicted in blue. The data comes from a tempo detection algorithm that as you might have guessed is not the best in town, the ...
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1answer
47 views

Proper Weighted Average

If I have a 3x3 matrix of information where the row totals describe the total goods produced by a particular company and the column totals provide the total for a particular type of good for all ...
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2answers
49 views

Simple integral related to average value of a function

Prove that $\displaystyle \int_0^{\frac{\pi}{2}} \sin^2 x\ dx = \int_0^{\frac{\pi}{2}} \cos^2 x\ dx$ by making the change of variable $x = \frac{1}{2}\pi - t$ in one of the integrals. This problem ...
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2answers
109 views

Algorithm for finding lowest average grade difference

Given a class with n boys and n girls, in which the girls recieved the grades P1,...,Pn, and the boys recieved the grades S1,...,Sn in an exam, find a pairing of girl-boy in a way that minimizes the ...
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1answer
27 views

Normal Distribution with Regards to Time and Percentages

The length of time for students to complete a test is found to be normally distributed with mean 70 minutes and standard deviation 12 minutes. How long should the time for the test be if we wish for ...
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1answer
84 views

Calculate average speed with unknown variable accelaration

I am in the middle of a vehicle tracking project where I have to calculate the distance traveled by the vehicle in a given amount of time. Data I am getting: ...
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0answers
59 views

Minimum sample size to obtain population mean?

Knowing the average of a population, how could I evaluate an expected sample average based on k_sample? Data Info: Variance and standard deviation: $\sigma^2= 0.18500975256337462$ ...
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2answers
585 views

Normalizing data to a given value.

I would like compare the data by normalizing it to a given value. for example: [20,30,40,50,60,70] How do I normalize the given set of elements to its first value, ...
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0answers
109 views

How to find “approximate most common” value from a list of RGB values

I have about 50 equally sized photos of magazine covers, which I'm attempting to blend into one composite image that shows the "average" cover. Each of the covers has a single face on it, so the ...
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1answer
51 views

what “average” to use that will give the most relevant value f0r portfolio

My assignment requires me to find return on capital, industry wise for the loan portfolio classified into various industry/sector, the data fields are : ... Name of account|industry|Outstanding ...
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1answer
29 views

What is the average value of number-range along interval?

Given a finite range of real numbers $$x = x_0,x_1,x_2,...,x_n$$ and an interpolation function $f(c), c\in[0..1]$ (such that e.g. $c(0)=x_0$, $c(1)=x_n$), and an interval $$I =[u,v], u\in[0..1], ...
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1answer
36 views

Probability question help

A company that sells annuities must base the annual payout on the distribution of the length of life of the participants in the plan. Suppose the distribution of male participants' lifetimes is ...
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0answers
58 views

About a special way to find the average waiting time to get a sequence

A friend of mine taught me the following question: You have a coin. When you toss it up, heads you note $1$, tails you note $0$. Then, tossing it up repeatedly, let's find the average waiting time to ...
0
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1answer
117 views

different types of Averages : prove there is an inequality between different averages

This is something I have been curious based on observations I have made by analyzing data from the energy industry. The context is you have monthly data for energy used per month and the cost per ...
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1answer
83 views

Find the value of each number which derives an average given a starting point, end point and total of numbers used.

Given an average, a low number, a high number and the total amount of numbers used (stated) to derive the average, is there a formula to determine what the value of each number was, that amounted to ...
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2answers
75 views

Is there another name for power mean, where p=1/2

What would you call this type of average? $\left(\frac{1}{n} \sum_{i=1}^n \sqrt x_i \right) ^ 2$
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0answers
540 views

Averaging equation?

Is there any name for following averaging equation and how does it work? $$ y_{i+1} = (1-\alpha)\times y_i + x_i $$ I'm using it to average a signal, but I'm not sure am I interpreting the results ...
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1answer
214 views

Continuously sampled event: Estimating the value of a future data point, based on past measurements and their tendency

Problem I'd appreciate some ideas on how to define a formula to estimate the value of a future data point for a continuously sampled event, based on past measurements and their tendency. At any ...
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1answer
79 views

How to calculate variance on spending?

My maths is a little rusty, but I understand how to calculate variance in general. A colleague asked me if I knew how to calculate the percentage variance on budget spending. Given this example: ...
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0answers
189 views

Need algorithm to take “max” of scores, but with “quality” weighting

I have an application where I get a small number of scores from medical tests (the same test repeated a few times) and I need to combine them. Normally the highest score would "win" in this ...
0
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1answer
54 views

Which of the following cannot possibly be the average - Standardized Test

I came across a question while preparing for a standardized test that is kind of confusing. Hope you guys could help me out here. The question is: Three men have weights that range from 110 to 135 ...
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1answer
423 views

Error propagation and averages, a practical question

Ok, I'm sure this is simple, yet I'm confused. Lets say my goal is to obtain an average concentration C=N/V so I take a number of N and V readings with errors: $N_1=50\pm2, V_1=100\pm4$ ...
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1answer
616 views

Charting Histogram Averages and Standard Deviation

Pretty basic question I'm sure: I have a 100 histograms, they are all created from randomly sampling the same data 100 times. Now, I want to show the 'average histogram' with markers at +1 standard ...
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votes
3answers
2k views

formula for converting a very long number to a fraction

What is the average (arithmetic mean) of 8, 7, 7, 5, 3, 2, and 2? the answer is $4\frac{6}{7}$. The sum of numbers is 34 and when you divide by 7 it's 4.8571428..... How can I get the fraction of ...
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votes
2answers
23 views

Average Attendance [closed]

I need to find a monthly average attendance. 3 out of 4 weeks were not counted. Do I take the number from the one week that was counted and divide by 4 or just use that one number as the average?
-1
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1answer
77 views

What is the meaning of |⋯| notation for an index subset?

I am currently working on a research project. In the attached image what does the capital $|I|$ and $|J|$ mean ?
-1
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1answer
75 views

Moving averages and crossovers in stock markets?

Suppose I take a two moving averages to analyse stock market prices - one $200$ day moving average, $m_{200}$, and another $50$ day moving average, $m_{50}$. How do you decide when to sell and when ...
-1
votes
1answer
614 views

Calculating a 5 star rating with a reputation number… [duplicate]

Possible Duplicate: 5 star ratings. Bayesian or Weighted average? Similar question, but unlike that question this deals with two factors the stars and reputation. Lets say Stack Exchange ...
-1
votes
1answer
2k views

Normalizing a matrix using matrix operations

I need some help in normalizing my matrix. I have a 5X4 matrix A. I want to normalize each column. Following is the explanation on the operations B = Operation of matrix (A) B matrix is 5x4 matrix. ...
-1
votes
1answer
196 views

Applying fuzzy logic to determine the degree to which a project is complete

I have a Project made up of tasks. Each task has an estimated completion percentage. I realise I could treat each tasks completion percentage as a representation of the degree of membership to the ...
-1
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1answer
2k 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: ...
-2
votes
1answer
55 views

Dropping the lowest number in a set lowers the mean average of the set.

So a friend of mine had her grade drop because her teacher had decided to drop the lowest grade. Is this possible or did the teacher mess up something? And if so, then how is it possible. We've ...
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votes
2answers
2k views

How to calculate MEAN of exponential distribution?

$ f(x) = \begin{cases} \frac15 e^{(-\frac15x)}, x>0 \\ 0, \text{elsewhere}\\ \end{cases}$ How to calculate $E[(X+5)]$ and $E[(X+5)^2]$ ? Thanks a lot.
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1answer
32 views

What time should Celia aim for in her sixth race to make the team? [on hold]

To be on the 1-km race team, Celia must have a mean time less than 5 min 50 sec in her 6 tryout races. Her times in 5 races are: 6 min 2 sec, 5 min 53 sec, 5 min 45 sec, 6 min, and 5 min 34 sec. What ...