The sum of several numbers divided by their count nicely summarizes the overall size of the numbers involved in a single value.

learn more… | top users | synonyms

0
votes
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 ...
0
votes
1answer
101 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 ...
0
votes
3answers
75 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 ...
0
votes
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 ...
1
vote
0answers
120 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 ...
0
votes
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
votes
0answers
23 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 ...
0
votes
1answer
28 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
votes
2answers
182 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 \\ ...
0
votes
0answers
44 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 ...
0
votes
2answers
23 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?
1
vote
3answers
67 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 ...
1
vote
2answers
56 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 ...
0
votes
2answers
47 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 ...
0
votes
1answer
42 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
votes
1answer
18 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
votes
1answer
113 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 ...
0
votes
2answers
44 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 ...
0
votes
3answers
821 views

How to find the total amount from given percentage

I am trying to answer this question from internet for my mathematics practice. ...
0
votes
1answer
45 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 ...
0
votes
1answer
40 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
votes
1answer
23 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
votes
1answer
65 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 $r(p)$ ...
39
votes
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
43 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
817 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
votes
0answers
36 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
votes
1answer
32 views

Calculating weighted score of test

I have a test containing questions with 3 levels of difficulty: ...
4
votes
1answer
597 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 ...
1
vote
2answers
37 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.
0
votes
0answers
52 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
votes
0answers
31 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
votes
1answer
148 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
votes
1answer
50 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. ...
0
votes
0answers
179 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
votes
1answer
40 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 ...
2
votes
0answers
60 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 ...
0
votes
1answer
32 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
votes
0answers
42 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 ...
3
votes
3answers
63 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 ...
0
votes
1answer
28 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: ...
1
vote
1answer
60 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
89 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. ...
1
vote
2answers
3k 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
178 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
votes
1answer
54 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
votes
0answers
37 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
votes
2answers
68 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
24 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 ...
0
votes
0answers
34 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 ...