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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6 views

Moving average with negative values

I want to calculate the radius of curvature of a meandering river. I have done a first estimated using a tool in arcgis. These are the results. The values of -99999 are recorded for points of no ...
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2answers
35 views

Estimated wait time for a library book

A library has 20 copies of a book that circulates for 3 weeks. All copies are out and there 40 people on reserve ahead of me. How do I estimate the wait time?
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1answer
28 views

Basic algebra problem for weighted averages

This question has me completely stumped for some reason, I would appreciate a bit of help. If you have 20 pounds of coffee for $1.80 a pound And then add X amount of coffee for $1.44 a pound How ...
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1answer
13 views

Mean of a discrete function

I have a set of finite variables (~20) which when plotted are forming a decaying exponential function. I want to know is there a better way to calculate the average of this function than by just ...
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1answer
36 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 ?
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1answer
35 views

Average value of function that converges?

I have a function $f$ that converges to a value: $$ f(x) = 1−s−A \beta ^ x $$ Where $A \in \mathcal{R}$, and $0< \beta <1 $, $0< A <1 $ I want to get the average value of for $ x > ...
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1answer
25 views

Average of Numbers

Consider the following problem: if $a \leq b \leq c \leq d \leq e \leq f \leq 101$ and if average of these(a,b,c,d,e,f) numbers is 100 then what could be the least value of a?
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0answers
8 views

Averaging of a product of fast oscillating function and slow oscillating one

Let's have a product of fast oscillating function and some slowly oscillating function: $$ F(\mathbf r) =f(kz)g(\mathbf r), \quad f(kz) = cos^{2}(kz),sin^{2}(kz). $$ I want to average this quantity ...
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1answer
24 views

How can I understand a formula written in this format. I am a beginner.

$$\bar{l}(\mathcal{P},\mathcal{L}) = \sum_{j=1}^n p_j l_j$$ I have just started studying this module and it describes the equation as the the average length of the code. Can you please break ...
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1answer
25 views

In data compression this equation describes the 'average length' of the code. Can someone please explain?

$$\bar{l}(\mathcal{P},\mathcal{L}) = \sum_{j=1}^n p_j l_j$$ I have just started studying this module and it describes the equation as the the average length of the code. Can you please break ...
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2answers
16 views

What is the Term for the Center of Mass Equation Structure

What is the term for the generic structure of this form of equation: SUM(Mi * Xi) / SUM (Xi) It is the same as the center of mass calculation.
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3answers
26 views

Average speed question of a car on an oval track

On an oval track, a car averages $30$ M.P.H. (miles per hour) for the first lap (a lap is $1$ mile around the track). At what average speed must that same car drive the 2nd lap on that same track so ...
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1answer
14 views

Simplifying an indefinite integral representing the calculation of an average

I have an equation for a term $z_i$: $$ z_i = \ln\frac{a_iR+p_i}{T_o* tan\theta_i } $$ This represents a value in a grid, at location $i$, with the grid representing a geographic area. To get the ...
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2answers
25 views

A Percentage of Averages

A company brags about the speed of their service, "75% of our assignments are completed in an average of 20 days." Is this a meaningful claim? Or is it kind of like saying, "60% of the time, it ...
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1answer
13 views

How do i find weighted normal vector?

How do I find the weighted average of a normal vector. Heres a phrase from my book a weighted average might be used where the weights are determined by the areas of the polygons (e.g., polygons with ...
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1answer
42 views

Integral representing average value [closed]

Consider the average value of $e^{-(x-y)}$ on the square R of side 2, centered at the origin. Write a double integral representing this average value(but do not evaluate it.) Without evaluating this ...
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3answers
79 views

Probability of two normal random variables when random samples are taken from a population

This is sort of second section to my previous question, I should have included both together, but I forgot to. Sorry for any inconvenience. X= random height of a male Y= random height of a female X ...
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2answers
125 views

Probability of a normal random variable added to a number being greater than another normal random variable, and distribution of average

$X$= random height of a male $Y$= random height of a female $X$ and $Y$ are independent of each other For $x$, $\mu=180\text{ cm}$ and $\sigma^2= 16\text{ cm}^2$ For $y$, $\mu=170\text{ cm}$ and ...
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0answers
21 views

Is this a proper formula for return rate?

Suppose we want to find the return rate of a casino game. For example, if a player brings 1000 USD to the game, pays a total cost of 1000 USD to play the game, regardless of the amount won (I will ...
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2answers
29 views

Calculate the average as numbers arrive

So, suppose you have to calculate the average of a set of numbers, but you don't know the whole set yet. Someone is providing you one number after the other and you cannot use more than the current ...
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0answers
19 views

Are these two approaches to calculating return rate mathematically consistent?

I have coded two C# programs, which use two different approaches to evaluate the outcome of a certain casino-style game (casino-style in the sense that the user pays points to take a turn, and ...
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1answer
14 views

As stock prices travel down what formula would you use to break out of a position

Suppose you are trading stock and you do not enforce a stop loss. Instead, you allow the stock to go where it wants. At some point, the value of your stock has dropped significantly and when the ...
2
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1answer
48 views

Average question GRE

The average daily temperature from 9th to 16th January(both inclusive) was 38.6 C and that from the 10th to 17th January(inclusive) was 39.2 C. what was the temperature on 17th January? I am able ...
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1answer
45 views

Meaningful statistic measure of data pairs

I have a dilemma. I have pairwise data, (a,b), that represents some form of speed, whether it's miles/hour or megabits/second. Let's say that we have the following set of data from measuring the ...
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1answer
39 views

Funny problem. How to average over periodic numbers

I'm want to calculate the average day and respective month that a specific event happens in a sample of countries. So for each country I have the date (one per year) of the particular event. Now my ...
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2answers
25 views

statistics z score

I'm curious what the phrase "on average" means. Here is an example: On average, 30% were further than ___ kilometers away when they had their accident. Is $30\%$ a $z$-score or is it a mean? ...
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0answers
14 views

For what kind of a profile will the average of the square be greater than the square of the average by a factor of 2?

For a dependent variable, say $\textit{A}$ and independent variable, say $\textit{t}$, what kind of a profile/graph will $\textit{A(t)}$ trace if the condition below is satisfied. ...
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1answer
19 views

Fair distribution

I have an user, who received one score in 3 different things for example in A, B and C. I ...
5
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1answer
102 views

Find center of mass of triangle with varying density

My objective: Find the center of mass of a thin triangular plate bounded by the y-axis and the lines $y= 7x+3$ and $y= 36-4x$. Assume that the density is given by $\delta(x,y) = 7x+2y+2$. In ...
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0answers
12 views

Application of Statistics in Sports Pool Selection

I am looking for the best mathematical approach for my hockey pool selection based on statistics from the previous season. We are 8 participants. Each participant must select: 9 Forwards 4 ...
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4answers
19 views

Percentages not adding up

I have a series of percentages: 132/220 (60%) and 88/220 (40%). Now when I break them down into subcategories and then recalculate the percentages them come out 5% different. 81/140 (58%) and ...
0
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0answers
15 views

What is the confidence level of a curve fitted moving average forecasting next element in time series?

Suppose I got a time series X={X1,X2,X3,...,Xn}, and i got a Moving Average of any kind, it doesn't matter. The moving average is curve fitted to the timeseries of n elements, to fit exactly and most ...
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1answer
18 views

Calculate the average grade Leslie must make in order to receive a B for the math class?

Leslie is taking a math class. This is how the class is graded. Test 1 13% Test 2 13% Test 3 13% Lab 1 10% Lab 2 10% Lab 3 10% Lab 4 10% Final Exam 21% She received a 93% on Lab 1, 70% ...
3
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1answer
113 views

How to find the function $f$ that satisfies $f(x, y) = f(x^{-1}, y^{-1})^{-1}$ and $f(x, y)$ is $\approx$ $average(x, y)$?

Fist of all, I'm a programmer, not a mathematician, and I'm sorry for my non native English. And I'm sorry if the question is not appropriate, it is my first time here. Or if the question has no ...
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0answers
4 views

Compute mean of a set from a biased sample

I want to compute the average of an unknown set $S$ containing real numbers. I can take arbitrary large number of samples from $S$, but the samples are not uniform, meaning that some numbers are ...
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1answer
42 views

calculus integration, average height of point on semi circle

i was recently watching a single variable calculus video of mit 18.01, lecture 23. in that it is said that average height of a point on semicircle with respect to arc length is 2/pi.I have a hard time ...
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3answers
47 views

How to compute Final Grade with assignment weightings?

I have just finished the Final for my Computer Hardware course, and I'm trying to figure out where my grade currently stands. The way the class is broken up is 50% weight for the homework, 25% for the ...
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2answers
30 views

Suppose the height $(m)$ of a ball is modeled by $s(t) = -4.9t^2 + 24.1t + 2$ where $0 \le t \le 5$ [closed]

Suppose the height $(m)$ of a ball is modeled by $s(t) = -4.9t^2 + 24.1t + 2$ where $0 \le t \le 5$ Find the time when the ball is 1m off the ground What is the function for average velocity from 1m ...
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0answers
56 views

About Bayesian formula and rating system

I'm building a scoring system with score from 0 to 5) and I would like to sort products according to the number of reviews and their scores. After some research on the Internet I have found two ...
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1answer
17 views

Getting the average of values with errors.

I have five data values each with an associated error. I want to find the mean of these values but also take the errors into account. How do I do this? Lets say the data values and errors are: ...
0
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0answers
20 views

How does an increase in the order count in a conditional mean model affect the model?

How does an increase in the order count in a conditional mean model affect the model ,especially the effect on its filtering capacity, smoothness, lag ; while also its forecasting ability. By ...
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1answer
23 views

Statistics question regarding mean of exponential distribution

So I have a question in front of me which reads: 'If component lifetime is exponentially distributed with parameter,obtain an expression for the proportion of components whose lifetime exceeds the ...
3
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2answers
167 views

Expressing a summation using matrix algebra

Consider the $n \times r$ matrix $$\begin{pmatrix} X_{11} & X_{12} & \cdots & X_{1n} \\ X_{21} & X_{22} & \cdots & X_{2n} \\ \vdots & \vdots & \ddots & \vdots \\ ...
0
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0answers
20 views

Unweighted Mean of Percentages

I have come across an interesting problem, which I'm sure there must be a standard solution to, but lots of Googling hasn't yielded much (which may mean I'm well off track...). I am trying to ...
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2answers
22 views

Magnitude of Average Velocity

A train travels 100 miles toward 37 degrees northwest and then 90 miles north. The whole journey takes 2 hours. What is the magnitude of the average velocity of the train?
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64 views

Find the average test score for each of three groups, given overall averages

I've been working on this question for the last hour and cannot determine a solution. Q: 100 children, 200 teens and 300 adults write a test and an average is computed for all three groups. The ...
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2answers
38 views

Where should I use median instead of average?

Is there a general law, or rule of thumb, or rationale, when to use median and when average? Although I know the difference and how they are computed, when I try to translate to simple English I ...
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2answers
34 views

What exactly does the Geometric Mean actually mean ? When should I use it?

I am working signal demodulation and the RC value requires to be the geometric mean of the periods of the message signal and the carrier wave. I wonder why I need the geometric mean for this or why ...
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1answer
39 views

Estimating how much two probability distributions differ

I have two probability distributions A and B. First I would like to estimate how much they differ. In this regard I use as metric the Jensen–Shannon distance (i.e. the square root of Jensen–Shannon ...
0
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1answer
17 views

In the loop average computation

I want to compute the average of a set of number, which is constantly increasing. I guess it's simple, but I'm struggling here: Let's say: 1st iteration: m(i)=a+b/2 2nd iteration: m(i+1)=a+b+c/3 ...