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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2answers
24 views

General forumla for taking running average of a running average?

Let's say I have an array of $N$ numbers: $n_1, n_2, .... n_N$ I then calculate a running average of those numbers, by averaging $A$ numbers at a time, which will result in the following array: $...
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1answer
28 views

Calculate new average from two other averages with its respective totals/counts

I have the next film named Blade Runner and it has two version (director cut and theatrical cut) and I rate the director cut with a 7 and the theatrical cut with a 8, so the average would be: (7 + 8) ...
0
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1answer
36 views

Midpoint between two real numbers

Well, it's quite clear that if I try to count mean average of any two numbers, I always get the midpoint. Is it really the whole intuition behind this concept? Or is there something hidden behind this ...
0
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1answer
27 views

Calculate average lifespan

We want to calculate the average lifetime of our customers. For each customer we know when they joined, whether they are still with us and if not, what date they left us. Our company has exponential ...
0
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1answer
15 views

Mixture & Alligation problem

In what ratio must a person mix three kinds of wheat costing him 1.20,1.44 and 1.74 dollars per kg., so that the mixture formed is worth 1.41 dollars per kg? a)11:77:7 b)12:7:7 c)ratio other than a ...
3
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4answers
101 views

Determine drug concentration over time, given its halflife and dosage

I want to calculate which of two doses is going to have the most active ingredient over the total time of an experiment. So as an example let's say I have a drug which has a halflife of 5 hours, and ...
0
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0answers
20 views

Determine contribution percentage

I'm trying to determine the individual category percentages once their weights have been applied. The easiest way to describe what I'm asking is to show my workings: ...
1
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0answers
35 views

Median of medians vs. single median

I have 10 sets. Each set corresponds to a user. Each set contains a different amount of floating point numbers. Each such number corresponds to a response time (of a user). Now I would like to ...
1
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1answer
22 views

Calculate average time of person in system when ins and outs are roughly equal

I have a system that has people going through a sensor for in, a sensor for out. I'm measuring ins and outs through the day, ...
1
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1answer
62 views

How can I curve a test grade knowing only the average and the highest score?

I am trying to get a raw score for my test grade, but I don't know anything about the distribution of test grades; all the information I have is the average and the highest score (and of course my own ...
1
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0answers
13 views

Do I need to calculate the weighted average in these cases?

I'm aware of the concept of calculating a weighted average but the data I'm working with is confusing me. I couldn't find any similar examples when I did a search. Here's an example. We have a number ...
0
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2answers
61 views

A can do a job in three hours, B can do it in 4. Hjow long does it take them together?

As it says in the question: if one person can do a job in 4 hours, and another can do the job in 3 hours, how quickly can they do the job together in they can work together? My attempt was this: ...
0
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0answers
10 views

Does (messing up) FIFO affect average cycle time?

I'm currently in the midst of a corporate class on process improvement and ran into the following situation: Workflow process containing several steps. No step is skipped or done out of order. ...
1
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1answer
51 views

Attaining the expected value over iterations

Is my implementation of the expected value correct? I conclude that the average number of iteration of this algorithm will be 1/3, but seems completely wrong. Rand() outputs either 0 or 1 (uniform) ...
-2
votes
1answer
63 views

Simultaneous Equations. [closed]

Erin goes off on a long bike ride at 10km/h. One hour later her brother starts chasing after her at 16km/h. How long will it take Alistair to catch up to Erin? Solve with simultaneous equations.
4
votes
2answers
43 views

Maximise difference between mean and median

I have a set of numbers and I want to maximise the difference between the mean and the median by removing a given number of elements. For instance I have the following set: ...
1
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2answers
35 views

Average $y$ from a range of $x$ in a parabola

Given a parabolic/quadratic formula such as $ax^2 + bx + c =y$, how do I get the average value of $y$ given a range of $x$ ($x_{min}$ to $x_{max}$). Real world example: if my formula represents the ...
3
votes
2answers
62 views

How do I properly average these percentages?

I have attendance records for an annual event: person 1: $4$ of $8$ attended $= 50.00$%, or every $2$ years person 2: $1$ of $4$ attended $= 25.00$%, or every $4$ years ...
1
vote
2answers
80 views

Calculating the average speed of a trip when given 3 different speeds for 3 percentages of distances.

The question: In a trip, $10$% of the way, Lucy drives uphill at an average speed of $56$mph; $10$% of the distance is downhill where she can manage an average speed of $72$mph. On flat ground, Lucy ...
0
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0answers
27 views

Average number of $5$-card draws before all $52$ cards in a deck are drawn.

So an interesting question was brought to me today and I'm not sure how to formulate the equation to answer it. A person draws $5$ cards from a deck, writes the cards down, puts the cards back in the ...
1
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0answers
19 views

Approximate values from point groupings

Say I am given a set of values: \begin{bmatrix}0.9&1.1&1&1.95&2&2.05&2.95&2.95&3.1&3\end{bmatrix} Is there a way I can get the 'center' or 'average' values 1, 2, ...
0
votes
0answers
10 views

Multiple server queuing model

I have come across the following problem in one of my courses: Let's suppose a patient in a hospital is waiting to be picked by one of the two doctors available. The time till a new pacient arrives ...
1
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2answers
17 views

Using double integration to compute an average yields a different result than computing it without integration

I'm self-learning multivariable calculus and am using double integration to compute the average value of $f(x,y)$ over some region. I'm trying to solve the following simple problem using two different ...
0
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1answer
15 views

Generalizing exponential moving average to n samples

Assume that we have a moving average like this: $E_t = a*S_{t-1}+(1-a)*E_{t-1}$ where $E$ would be an estimate we are interested in, and $S$ is a sample we take at each point in time. Now, if we ...
1
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0answers
29 views

Averaging speeds

I read the answer to this question: http://stackoverflow.com/questions/34794664/how-should-i-calculate-the-average-speed-by-road-segment-for-multiple-segments/34795821#34795821 Can anyone please ...
0
votes
2answers
36 views

Find the percent of boys and girls

I have a basic school academic question which despite of trying very hard I was unable to find a solution - Average score of girls is an exam is $67$ and that of boys is $62$. Find the percentage of ...
1
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3answers
46 views

Number of Likes and Dislikes to Star Rating system

I have a 5 star rating system that outputs a recommendation. A user inputs a rating based on a Like or Dislike. What I would like to know is how to convert the number of likes and dislikes into a ...
0
votes
0answers
30 views

Weighted average of unit vectors

I am trying to determine the yaw (z) axis of a vehicle given a bunch of sensors, each of them subject to different kinds of error. This means I get a bunch of unit vectors for the z axis, expressed ...
0
votes
1answer
44 views

Calculating a weighted average for different pay rates and different hours.

I'm trying to take the money earned over several days - each with unique hours worked and dollars earned per hour (hrs and $/hr). What I've done is multiply each days' # of hours by its rate to get ...
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votes
1answer
36 views

Average velocity question? [duplicate]

I usually know how to do these but this one gives me trouble. If a ball is thrown into the air with a velocity of 46 ft/s, its height in feet t seconds later is given by $y = 46t − 16t_{2}$. (a) ...
0
votes
1answer
27 views

If I subtract a number (from a sequence) from the average of all the numbers in that sequence - what do I have?

If I have a number (from a sequence) and I then subtract that number from the average of that sequence- what do I have? I would describe it as a 'deviation from the average' - but is there a better ...
0
votes
1answer
12 views

Weighted Averages from the world of GMAT..

I am really confused about how this question has been solved. I've given the question, author's approach and then mine. Can you help me figure out why/ why not I have gone wrong? Thanks in advance, ...
1
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1answer
28 views

Average case of element comparisons when searching for an element x with a specific probability

I just had a midterm, and unfortunately our professor has stated that he will neither discuss nor post any solutions to the midterm, so I'm posting a question that was on it here in hopes that someone ...
0
votes
1answer
71 views

How can I average two integers digit by digit?

I would like to take two integers of similar size (about the same number of digits) and average them, without having to first add them, and then divide the result by two. Let's say I have the ...
0
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0answers
32 views

How to find the best-case and average-case number of comparisons performed by a comparison tree?

So I'm reviewing some material before a midterm tomorrow and I came across this question: ...
-1
votes
1answer
29 views

Specific average calculation [closed]

Suppose I have a set of weighted grades for a subject in high school. Like this: 8.4 (weight: 3), 7.2 (weight: 1), 3.4 (weight: 3). When I loop over that set like ...
1
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1answer
44 views

For all real a, b, order the averages.

I'm taking a proofs class and the textbook says to do this problem: For all real $ a, b > 0 $, show $ \dfrac{2ab}{a + b} \leq \sqrt{ab} \leq \dfrac{a + b}{2} \leq \sqrt{\dfrac{a^2 + b^2}{2}} $ ...
0
votes
0answers
71 views

Calculating the average case complexity for finding the maximum number in an array

Algorithm: Given a non empty array with $N$ Numerical values, the algorithm finds the location LOC and the maximum value MAX of the largest element of DATA. Initialize K:= 1, LOC:=1, MAX:=...
0
votes
0answers
238 views

Working out averages for goals scored per football game

If for example I had a sample set of 11 football games. Of those 11 games, there were a total of 8 goals. So I can work out the average goals per game by ...
1
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1answer
35 views

Given the lengths of two sides of a triangle, is it possible to obtain (sharp) bounds for the average length of the sides of the triangle?

The title says it all. Given the lengths of two sides of a triangle, is it possible to obtain (sharp) bounds for the average length of the sides of the triangle? Let the lengths of two sides of ...
1
vote
1answer
21 views

What is the difference between the natures of finding average value using secant slope and integral?

To my knowledge, there are two ways of finding average (what average I am not too sure, forgot what my teacher said. But I think it has something to do with the mean value theorem) Say you have a ...
4
votes
1answer
44 views

What is the name of this type of “average”?

Given two variables $x$ and $y$, $$\frac{2}{1/x + 1/y} $$ looks like some kind of average of $x$ and $y$. Is there a name for it? Where can i look up more information (such as properties) of this ...
1
vote
1answer
48 views

formula to calculate average quiz score

I'm creating a Quiz web application for an assignment. There is a requirement to show a user the average score for a particular quiz (from pool of all users who have tried it before) upon successfully ...
0
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0answers
47 views

Time series analysis, moving-average model, ARMA model

I'm reading documents about time series analysis, including Autoregressive–moving-average model, Moving average model, Wold's theorem, etc. The notation MA(q) refers to the moving average model of ...
0
votes
0answers
57 views

Is exponential decay a moving average filter?

I learned that a moving average filter is an FIR filter that gives the average of $N$ previous inputs, like this: $y_n = \sum_{i=0}^{N-1}\frac{x_{n-i}}{N}$ As a simple extension, it might be some ...
0
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0answers
37 views

Calculating Average “Productivity”

Let me apologise in advance if my terminology is incorrect or if what seems logical to me is completely nonsensical. I am an analyst without a mathematical background and have tried to self teach off ...
0
votes
1answer
26 views

Generate exponential weights (sum of all = 1)

I have $500$ observations and I want to make exponential weighted average of them. I want the weights to be something like $w_i = 0.999^t$ when $t$ is from $1$ to $500$ (num of observations). ...
1
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5answers
291 views

Is the point of a shape with the greatest average ray length also the “centroid”?

By a shape I mean one with a enclosed area. One example can be with $x^2+y^2+\sin{4x}+\sin{4y}=4$. I am dealing with implicit relations on a 2-d plane. By the "ray length" I mean the length of the ...
3
votes
2answers
114 views

In what sense is the “average” of $sin(x)$ equal to 0?

I think it makes intuitive sense that if a phenomenon is described by simple sinusoidal oscillation, it is "on average" equal to its midrange, but I think I failed in trying to make that statement ...
-1
votes
1answer
38 views

One number to represent the percent changes of multiple numbers

Question: Is there a way to represent the total percent change of multiple numbers (make it into one number that represents change) that isn't just the percent change between the first and last number ...