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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1answer
22 views

rate of change and the “1 - 10” scale [on hold]

I am using the 1 - 10 scale for pain management in therapy. And I was wondering, when a patient says there pain is a 4 out of 10 one week, then the next week the say it's down to a 1 out of 10, that ...
0
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1answer
32 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
15 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 ...
0
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1answer
12 views

Help with creating a formula to calculate grade needed on test to pass?

This is probably a simple math question and yet I'm struggling to understand it, any help would be extremely appreciated. Say if I have 2 test results, 50% on Test 1, test worth is 10% of final ...
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0answers
31 views

Calculating Expected Value when terms involve Max and Summations

Suppose $A= \sum_{k=1}^{n/2}X_i$ and $B=\sum_{k=n/2+1}^{n}X_i$ $X_i$ is a random variable which takes on values 5,6,7 and 8 with equal probability. What is expected value of ...
-4
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0answers
21 views

Approximate average [closed]

a restaurant records the amount of time customers wait for a table on saturday evenings. The table to the right lists the frequency of wait times for the last $100$ customers. ...
0
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2answers
37 views

Using difference of average for identifying features in an image

I'm working with this paper: Textural Features Corresponding to Visual Perception, by Tamura, Mori, and Yamawaki. There's a part where you have to calculate neighborhoods of one image (matrix of, for ...
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3answers
38 views

How to find the total amount from given percentage

I am trying to answer this question from internet for my mathematics practice. ...
-1
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1answer
31 views

How to solve averages without using formula

For the question, "The average of $30$ numbers is $40$ and that of other $40$ numbers is $30$. Find average of all numbers.", the options given are: $35$ $34$ $34\frac{1}{2}$ $34\frac{2}{7}$ I ...
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1answer
22 views

Finding the average of multiple ranges

I conducted a survey where participants inputted a range for their weekly tablet usage. For example, someone was able to say they used their tablet "11 - 15 hrs/week". How do I find the average ...
0
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1answer
10 views

Power of a square wave signal

I have a signal with half-amplitude $A$ and period $T$ and I want to calculate the average power of the signal. I think I remember the power of a signal $x(t)$ to be ...
2
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1answer
29 views

Average Number of Roots of a Polynomial modulo p

Let $f \in \mathbb{Z}[X]$ be an irreducible non-constant polynomial, and consider this polynomial modulo $p$ for each prime $p$. On average, how many roots does $f$ have modulo $p$? I.e., if $r(p)$ ...
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11answers
7k views

What is the average of no numbers?

I have two programs that both behave nearly identically: they both take in any numbers you give them and can tell you the average and how many numbers were given. However, when you don't give them any ...
2
votes
2answers
37 views

Average Growth Rate for Year 1 across 5 groups

Lets suppose that I am measuring the total number of online visitors to 5 websites on a monthly basis. I have this data for the months of Jan - Dec. What I want to understand is "What is average ...
1
vote
2answers
70 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 ...
0
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0answers
21 views

The use of Weighted arithmetic mean to determine the extent to which the data correspond

I don't know when I can ask such question, because it is not a completely mathematic question. I have a text and a topic (single word). I want to check how much this text corresponds to the topic. ...
0
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1answer
19 views

Calculating weighted score of test

I have a test containing questions with 3 levels of difficulty: ...
4
votes
1answer
545 views

Sum of averages to averages of sum

I have the following values $\overline{b}$, and $\overline{u}$ which is : $\overline{b} = \dfrac{b_1+b_2+b_3+b_4}{7}$, $\overline{u} = \dfrac{u_1+u_2+u_3+u_4}{7}$ is there any way I can get the ...
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vote
2answers
29 views

For any base-$n$ number system, what is the average length of a number $\leq100$?

By this I mean the amount of symbols (bits / digits / etc. ) for any number from $0$ to $100$. I don't know whether this can be answered, I'm just asking out of interest - not homework or anything.
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0answers
27 views

find the no. of wagons need to be attached

The speed of an engine is proportional to the square root of the number of wagons attached to it. Without any wagons attached to it the speed of the engine is 60km/hr. With 16 wagons attached to it ...
0
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0answers
24 views

Problem of EOQ under conditions of uncertainty

I have solved the following problem for one half. Please help me to solve it full. A restaurant offers, at noon, only one menu at a fixed price of Euro 15. The cost of each meal is 12 Euros. From the ...
0
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1answer
34 views

Find average stream velocity over a cross-section of a cylinder, given $v(r) = k(R^2 − r^2)$

I'm doing integration homework and a question that I am not sure how to approach popped up. The velocity (in centimeters per second) of blood r cm from the central axis of an artery is given by ...
0
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1answer
44 views

Calculating average over a year

I'm trying to calculate the average count of employees for a group of companies. I need to exclude months where a a company had no employees. Please verify that my approach is correct. ...
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0answers
54 views

Average and Standard Deviation for Angular Values

I'm trying to characterize an inexpensive accelerometer that provides (roll, pitch, yaw) values by generating basic running statistics (mean and standard deviation). But I'm unfamiliar with ...
0
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1answer
31 views

How do I “recalculate” a median number?

I'm not sure how to explain the question, so I'll do it by an example. The median age in some country is 41.7. 50% is younger than 41.7, 50% is older. How would I calculate the percentage of the ...
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0answers
56 views

Compute average and maximum value of a field over a streamline

I'm working on a code solving a set of PDEs. I have a vector field, $\vec{v}(x,\theta,z,t)$ (it's a velocity) and a scalar field, $c(x,\theta,z,t)$. I have a $2\pi$-periodicity in $\theta$. The ...
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1answer
26 views

Probability static area is greater than variable area

I have a rectangular section of constant height and length and I choose a random starting point anywhere along its length. From the randomly chose starting point, I first add ...
0
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0answers
36 views

What is this called specifically?

Imagine you take a radius from the center of the shape, you add up all of the lines as it rotates 360 degrees. The radius is measured from its point of rotation, like (0,0) in Cartesian coordinates,to ...
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votes
3answers
52 views

The average value of the function $y=\tan(2x)$ over the interval $[0,\frac{\pi}{8}]$

I was given the following question in a technology free exam. How would one go about solving this without the use of a calculator? NB. I am currently in my last year of high school so please don't ...
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votes
1answer
20 views

Average value for multiple integrals

If there is a function $f(x,y)$ and we want to find the average value over a region $R$ defined by $0<x<1$ and $0<y<x$, how is that computed? I know that it would be something like this: ...
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vote
1answer
30 views

Sum and sum of average not matching

I'm struggling with the following problem. I have a table showing the % of a population that like (say) bananas in three locations, the population of each location, and the total population who like ...
2
votes
1answer
40 views

Does “Expected Absolute Deviation” or “Expected Absolute Deviation Range” exist in stats and have another name?

So everyone is familiar with Variance and Standard Deviation from high school, but it seems no one has any familiarity with a philosophical justification for such weird, seemingly arbitrary measures. ...
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2answers
76 views

What is the difference between the normal average and weighted average?

What is the difference?For what kind of purpose do we use the weighted average method?Why don't we instead always use the normal average method?and also,how to get the weighted average of some ...
2
votes
1answer
168 views

Time to extinction

Suppose that a population has a rate of extinction equal to $k \exp({-\epsilon N})$ where $\epsilon$ and $k$ are constant and $N$ is the population size. This also means that the time to extinction is ...
0
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1answer
35 views

Help with finding the arithmetic mean of all the radii from the center to the edge of an ellipse?

So far I approached this problem computationally, I decided to take all the radii add them up, by distance formula, then divide by the number of radaii. To make the distribution even, I rotated the ...
0
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0answers
31 views

Problem calculating the average power of a vector?

I am calculating the average power of a vector. I would like to compare the final expression with the simulation. However, they are not equal. Please help me to point out which steps are wrong. Thank ...
0
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2answers
48 views

Computing the average difference in a list of numbers

I have a list of numbers 280, 449, 689, 959, 1360, 1740, 1139 so there is between 289 and 449 is a distance of 169 and then between 449 and 689 a distance ...
0
votes
1answer
19 views

Features of a Set Given Same Value for Maximum and Average

What else, if anything, can be said if the maximum of a set is equal to the average value in the set? If the average is equal to both the maximum and minimum then all the values are the same, but can ...
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0answers
25 views

Economics Marginal Cost and Average Cost

I am in Computer Engineering but this year the university gave me choice for two electives with one being Psychology and the other Economics...So this being my first economics course I am really ...
0
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1answer
37 views

How to normalize a slope?

Say I have two slopes and two averages for a sample: $m=4{,}000$ dollars/day, average $a=50{,}000$ $n=80{,}000$ dollars/day, average $b=700{,}000$ Graphically, $n$ is very ‘steep’ compared to $m$. ...
3
votes
1answer
33 views

Is the norm of the average $\le$ the norm of the max?

Given $\pmb X \in \mathcal{R}^p$, denote the elements of $\pmb X$ as $\pmb x_i$ for $i= 1, \dots, n$. Denote the $t(\pmb X)$ as the average of $\pmb X$ \begin{equation} \pmb t(\pmb X) = \frac 1 n ...
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vote
1answer
25 views

fast solve average

there are Indians and Europeans in an army of 12,000. the average height of Europeans is5'10" and that of Indians is 5'9" and the average height of entire army is 5'9,3/4. find out the number of ...
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3answers
38 views

Covariance Issue with a joint distribution

Here is the problem: Let $X$ and $Y$ be continuous random variables with joint density function: $$f(x,y) = \frac{8}{3}xy\text{ for }0 \le x \le 1\text{ and }x \le y \le 2x $$ I'm trying to find ...
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vote
2answers
84 views

How to establish this inequality: $(1-a)(1-b)(1-c) \geq 8abc$ for $a+b+c=1$?

Let $a$, $b$, and $c$ be positive real numbers such that $a+b+c = 1$. Then how to establish the following inequality? $$ (1-a)(1-b)(1-c) \geq 8abc.$$ My effort: Since $a+b+c =1$, we can write $$ ...
2
votes
1answer
44 views

What is the most elementary proof of these inequalities?

Let $p$ be a non-zero integer, and let $x_1$, $\ldots$, $x_n$ be $n$ positive real numbers. Then we define the $p$-th power mean $M_p$ of these numbers as $$ M_p \colon= (\frac{x_1^p + \ldots + ...
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2answers
30 views

Proving that mean KDR in a videogame is one

This is not related to schoolwork. A friend of mine challenged me to prove that the mean KDR (assuming players can only die at the hands of other players) must always be equal to one. I have gotten ...
0
votes
1answer
40 views

How to find the average value of a discontinuous function

A car covers $\frac{1}{3}$ distance with speed $20\frac{m}{s}$ and $\frac{2}{3}$ with $60\frac{m}{s}$. What is the average speed over the entire interval? Due to the discontinuity of the function, I ...
0
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2answers
27 views

Comparing / Averaging two very different numbers

I have two examples called a and b. Each example has two scores: a: 0.5 and 0.001 b: 0.8 and 0.0001 If the higher score wins, then b wins when looking at the first set (0.8 > 0.5). But I also want ...
0
votes
1answer
27 views

What ratio of students in a 20-student class with total average of 17.06 got at least 17?

The maximum score is at most 20. The class has 20 students. For math exam the average of the whole class is 17.06. How many per cents of the class got at least 17 out of 20 in the exam?
0
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1answer
25 views

Average sum of seria

I need some help with the next question in probability: In the range {1,2,...,100}, someone picks randomly 15 different numbers, with the same probability for each number. What is the average sum ...