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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2
votes
3answers
704 views

Averaging the values of $\cos x$ over one period

I'm calculating the average value of $\cos x$ by dividing the period $[0,2\pi]$ into ten intervals which means that I should be looking for the average of 11 results. What I get is approx. 0.09. The ...
1
vote
1answer
68 views

Calculating expected value

Here is the problem. In a game(shown below) with the marker in the center on each turn the marker moves to a neighbouring region with all positions equally likely and the player collects the cash ...
0
votes
1answer
110 views

finding average price of two lots of shares

Sorry, not a math guy, this might be an overly simple question for the lot of you, but it's a calculation that I'll have to do a lot possibly, so please show me the best way to do it. If I have $1265$ ...
3
votes
1answer
124 views

How do I average a new number into an established percentage if I know the number of items?

This seems like something I should be able to do but I can not for the life of me figure it out. I'm writing a program to calculate an average score; let's say that my data looks like this. x = ...
1
vote
1answer
42 views

Generating statistics from data samples, that are of snapshots.

My question is part math part computers but I need more of the math answer then a computer answer. I am going to be grabing snapshots of a moment of time on how a computer is performing. Because of ...
1
vote
2answers
2k views

How can I find the average y value of a function on a given domain?

Lets say that $f(x) = (10 - x)\ln x$. Over the domain: $1 ≤ x ≤ 10$. How can I find the average value of $y$ over this domain and what is that value?
1
vote
1answer
356 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: ...
1
vote
1answer
264 views

Estimating a sample mean using sub-sample means

we collect a lot of data on a daily basis via an API, and part of this data includes fields that represent sample means. Specifically, we get provided with a sample mean and the sample size, lets call ...
1
vote
1answer
122 views

Derivative of a 'weighted average' of decreasing fractions

I'm having some trouble showing the following statement (which intuitively seems to hold): Suppose I have a series of fractions indexed by $i$ , each of them a function of $N:f_{i}\left( N\right) ...
1
vote
1answer
340 views

Minimum Numbers to find the given average.

Average score of the player (sum of scores in all the games / no. of games) is given. How Can we find the minimum number of games the player should have played to achieve that average. scores are non ...
2
votes
1answer
710 views

Average delta value of a sequence of $N$ $8$-digit numbers

Given a sequence of $N$ $8$-digit numbers, how to calculate the average delta value, thanks.
0
votes
0answers
557 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 ...
1
vote
1answer
81 views

averaging STDs vs. calculating a single STD

I have a set of data points. I extracted the Standard Deviation for the whole set, and also extracted STDs for a partition of the points where each element of the partition has at least two points. I ...
2
votes
1answer
205 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, ... ...
5
votes
3answers
3k 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 ...
8
votes
4answers
3k views

Average bus waiting time

My friends and I were "thinking" yesterday in the pub about the following: if a person is standing on a bus stop that is served by a single bus which comes every p minutes, we would expect the average ...
1
vote
1answer
3k views

Average proportion for proportions with different denominators

Say I have an experiment in which subjects are asked to respond to some stimulus. Their responses are transcribed and coded, first as "Valid/Invalid", and then for the valid responses, ...
-2
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.
1
vote
2answers
2k views

Statistic Missing Value [closed]

A professor has recorded exam grades for $30$ students in his class, $1$ of the $30$ grades is unreadable. The mean score on the exam was $82$, and the mean score of the $29$ available scores is $84$, ...
1
vote
3answers
4k views

How do I find the average of a section of a curve?

I've done some research already and discovered that the formula I need to do this is $$\frac{1}{b-a}\int_a^b f(x)\;dx$$ With $a$ and $b$ being the start and end points of the section of curve I want ...
2
votes
2answers
289 views

Least Squares Fit

So here's the question: Given a collection of points $(x_1,y_1), (x_2,y_2),\ldots,(x_n,y_n)$, let $x=(x_1,x_2,\ldots,x_n)^T$, $y=(y_1,y_2,\ldots,y_n)^T$, $\bar{x}=\frac{1}{n} ...
2
votes
1answer
5k views

Average, standard deviation and min/max values

I'm analzying a computer science paper and just found in the experimental setup the following statement: Average (standard deviation) of number of files per peer: 464 (554) Min - max number of files ...
3
votes
1answer
2k views

Average Distance Between Random Points in a Rectangle

My question is similar to this one but for rectangles instead of lines. Suppose I have a rectangle with sides of length $L_w$ and $L_h$. What is the average distance between two uniformly-distributed ...
0
votes
2answers
395 views

How can i solve this problem about averages?

The average (arithmetic mean) bowling score of $n$ bowlers is $160$. The average of these $n$ scores together with a score of $170$ is $161$. What is the number of bowlers, $n$? I tried this: $$X'*n ...
0
votes
1answer
51 views

Formula for normalising with respect to average

I have a 5*5 grid (as in the figure). At each point there are 5 dishes of varying numbers of bacteria. I'd like to write a formula which calculates the average of these 5 and then divides by the ...
0
votes
2answers
336 views

given average score,find the selected numbers

Suppose average score of 46 scores selected from 1,2,3,4,5 is 1.65.Is there any way to find out which are the scores that are selected.
1
vote
2answers
78 views

Finding one value from a mean.

7 boys have a mean height of 1.80m. Peter joins the boys and now the mean height is 1.75m. Find Peter's height.
0
votes
1answer
43 views

Finding average of a sample with single piece of data

Is there anyway possible to guesstimate/estimate the average of a sample if you know just one of the sameple and its position when all available samples are arranged ascendingly and total number of ...
2
votes
3answers
282 views

Erased number?

A set of consecutive positive integers starting with 1 is written on the board. A student came along and erased one number. Average of remaining numbers is 61 15/20 . What was the number erased
6
votes
1answer
2k views

How to calculate an overall 5 star rating based on other weighted 5 star ratings

I have these 3 ratings. I want to combine them to produce an overall rating out of 5. The overall rating can be a float, so no rounding is necessary, but it cannot be negative. I'm just not sure ...
0
votes
2answers
1k views

What is a simple formula to interpolate 2 unknowns between 2 knowns?

What is a simple formula to find 2 intermediate values between 2 known values? f(1)=a, f(2)=?, f(3)=?, f(4)=b If there would be only 1 unknown, then it would be ...
0
votes
1answer
250 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 ...
0
votes
1answer
82 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: ...
0
votes
0answers
191 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 ...
2
votes
3answers
1k views

from weighted average to single values

think about when you're computing a weighted average: you do something like W = sum(amount*weight) / sum(weight) Now I need to find every amount (amount0, amount1.....) starting from knowing the ...
1
vote
2answers
156 views

Maximum Profit at which combination

A dealer deals only in colour TVs and VCRs . He wants to spend up to Rs.12 lakhs to buy 100 pieces. He can purchase colour TV at Rs. 10,000 and a VCR at Rs. 15,000. He can sell a colour TV at Rs. ...
5
votes
2answers
881 views

How many decimal places are needed for incremental average calculation?

If using the following formula to incrementally calculate average value: $$m_n = m_{n-1} + \frac{a_{n}-m_{n-1}}{n}$$ And the number of decimal places to where you can save $m_n$ is limited to $d$ ...
0
votes
1answer
404 views

Algorithm to Get a Product score based on rating

I am trying to device a algo for product score. Here are the inputs User rates a product on 5 different criteria out of 10 Each criteria has a different weightage with all adding up to 100% There ...
0
votes
1answer
1k views

Calculating Average Percent

I have two ways to calculate the average starting price of an auction item compared to it's actual value. ...
1
vote
0answers
59 views

Taking averages

Suppose I have a function $f(\theta)$ that is a function of the angle $\theta\in [0,2\pi)$. Why is the average of $f$ over a large collection of randomly oriented objects: $$\int f(\theta)\sin ...
2
votes
1answer
379 views

Error Metric which incorporates both mean & standard deviation of data in euclidean space

For simplicities sake (the actually problem is more complex)...Let say I have a set of n 3d points, whose position move over time. For all pairs, I have calculated the mean and standard deviation of ...
2
votes
2answers
146 views

Calculating statistic for multiple runs

I have s imple, general question regarding calculating statistic for N runs of the same experiment. Suppose I would like to calculate mean of values returned by some Test. Each run of the test ...
3
votes
1answer
125 views

Dirichlet Series and Average Values of Certain Arithmetic Functions

If an arithmetic function $f(n)$ has Dirichlet series $\zeta(s) \prod_{i,j = 1} \frac{\zeta(a_i s)}{\zeta(b_j s)}$, for which values of $a_{i}$ and $b_{j}$ is the following true? That \begin{align} ...
1
vote
0answers
41 views

Dynamic Light Scattering

In DLS does the combination of the Time Average and Ensemble Average give a better statistical average than the results shown by each case considered separately ?
2
votes
1answer
146 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
vote
1answer
232 views

How long does it take to complete a sticker album?

We are collecing stickers in chocolate bars and whenever we open a bar we get a random new sticker. There are many different stickers and we try to collect them all. We open the first bar and get a ...
2
votes
0answers
586 views

How can you calculate actual values when all you have is rolling averages?

Let's say you have a set of data that is rolling 6 month averages of the actual monthly data. Good data collection would mean you saved the actual values and then calculated the rolling averages, but ...
1
vote
2answers
56 views

Constructing an average equation - Standardized Test

A question in the standardized test is: The average of $n$ numbers is $a$. If $x$ is subtracted from each number the average will be a) $(ax)/n\quad$ b) $(an)/x\quad$ c) $an-x\quad$ d) ...
0
votes
1answer
55 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 ...
0
votes
1answer
367 views

Calculating average of word problem

I was preparing for a standardized test and came across the following problem: During a closeout sale 30 suits are sold at \$60 each.The price is the reduced to \$50 each and 20 suits are sold. At ...