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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99 views

alligation problem

Ravi lends Rs 3600 on simple interest to Harsh for a period of 5 years. He lends a part of the amount at 4% interest and the rest at 6% and receives Rs. 960 as the amount of interest. How much money ...
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3answers
47 views

Mean of a vector

Be a set of numbers $v=(a_1, a_2, \ldots, a_n)$ I want to form the following average vector $\mu = (\frac{\sum a_i}{n}, \frac{\sum a_i}{n}, \ldots, \frac{\sum a_i}{n})$. If I do it iteratively step ...
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1answer
95 views

Maximum and minimum average question

During a cricket match, India playing against NZ scored in the following manner: Partnership | Runs scored $1$st wicket$~~$ | $112$ $2$nd wicket | $58$ $3$rd wicket$~$ | $72$ $4$th wicket$~$ | $9$ ...
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1answer
79 views

problem in understanding overall change in average

The average weight of 5 men is decreased by 3kg when one of them weighing 150kg is replaced by another person. This new person is again replaced by another person whose weight is 30 kg lower than the ...
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0answers
29 views

higher order schemes or curvature to be smoothed

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
40 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
34 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
34 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
58 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
37 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
28 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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14 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
28 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
19 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
92 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
16 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
34 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
22 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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3answers
161 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
136 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
37 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
52 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
29 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
17 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
94 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
50 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
43 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
31 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
18 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
20 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
252 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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25 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
51 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 ...
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0answers
39 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
24 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% ...
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1answer
162 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
7 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
141 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
107 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
45 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
214 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
18 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
25 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
31 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 ...
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2answers
197 views

Expressing a summation using matrix algebra

Consider the $r \times n$ matrix $$\begin{pmatrix} X_{11} & X_{12} & \cdots & X_{1n} \\ X_{21} & X_{22} & \cdots & X_{2n} \\ \vdots & \vdots & \ddots & \vdots \\ ...
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1answer
71 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
26 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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73 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
89 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 ...