The sum of several numbers divided by their count nicely summarizes the overall size of the numbers involved in a single value.
-2
votes
2answers
388 views
How to calculate MEAN of exponential distribution?
$ f(x) = \begin{cases} \frac15 e^{(-\frac15x)}, x>0 \\
0, \text{elsewhere}\\ \end{cases}$
How to calculate $E[(X+5)]$ and $E[(X+5)^2]$ ?
Thanks a lot.
0
votes
2answers
58 views
How do I find the average of a section of a curve?
I've done some research already and discovered that the formula I need to do this is
$$\frac{1}{b-a}\int_a^b f(x)\;dx$$
With $a$ and $b$ being the start and end points of the section of curve I want ...
2
votes
2answers
150 views
Least Squares Fit
So here's the question:
Given a collection of points $(x_1,y_1), (x_2,y_2),\ldots,(x_n,y_n)$, let
$x=(x_1,x_2,\ldots,x_n)^T$, $y=(y_1,y_2,\ldots,y_n)^T$,
$\bar{x}=\frac{1}{n} ...
1
vote
1answer
759 views
Average, standard deviation and min/max values
I'm analzying a computer science paper and just found in the experimental setup the following statement:
Average (standard deviation) of number of files per peer: 464 (554)
Min - max number of files ...
3
votes
2answers
340 views
Average Distance Between Random Points in a Rectangle
My question is similar to this one but for rectangles instead of lines.
Suppose I have a rectangle with sides of length $L_w$ and $L_h$. What is the average distance between two uniformly-distributed ...
0
votes
2answers
73 views
How can i solve this problem about averages?
The average (arithmetic mean) bowling score of $n$ bowlers is $160$. The average of these $n$ scores together with a score of $170$ is $161$. What is the number of bowlers, $n$?
I tried this:
$$X'*n ...
0
votes
1answer
31 views
Formula for normalising with respect to average
I have a 5*5 grid (as in the figure). At each point there are 5 dishes of varying numbers of bacteria. I'd like to write a formula which calculates the average of these 5 and then divides by the ...
0
votes
2answers
35 views
given average score,find the selected numbers
Suppose average score of 46 scores selected from 1,2,3,4,5 is 1.65.Is there any way to find out which are the scores that are selected.
-4
votes
1answer
60 views
Doubts about Average, Proportion & Ratio
Question 1 : In a team of $11$ players the age of the captain is $26$ and that of the wicket keeper is $3$ years more than the captain. If the average of the ages excluding the captain age and the ...
1
vote
2answers
69 views
Finding one value from a mean.
7 boys have a mean height of 1.80m.
Peter joins the boys and now the mean height is 1.75m.
Find Peter's height.
0
votes
1answer
22 views
Finding average of a sample with single piece of data
Is there anyway possible to guesstimate/estimate the average of a sample if you know just one of the sameple and its position when all available samples are arranged ascendingly and total number of ...
3
votes
3answers
160 views
Erased number?
A set of consecutive positive integers starting with 1 is written on the board. A student came along and erased one number. Average of remaining numbers is 61 15/20 . What was the number erased
4
votes
1answer
204 views
How to calculate an overall 5 star rating based on other weighted 5 star ratings
I have these 3 ratings. I want to combine them to produce an overall rating out of 5. The overall rating can be a float, so no rounding is necessary, but it cannot be negative. I'm just not sure ...
0
votes
2answers
562 views
What is a simple formula to interpolate 2 unknowns between 2 knowns?
What is a simple formula to find 2 intermediate values between 2 known values?
f(1)=a, f(2)=?, f(3)=?, f(4)=b
If there would be only 1 unknown, then it would be ...
0
votes
1answer
68 views
Continuously sampled event: Estimating the value of a future data point, based on past measurements and their tendency
Problem
I'd appreciate some ideas on how to define a formula to estimate the value of a future data point for a continuously sampled event, based on past measurements and their tendency.
At any ...
0
votes
1answer
58 views
How to calculate variance on spending?
My maths is a little rusty, but I understand how to calculate variance in general. A colleague asked me if I knew how to calculate the percentage variance on budget spending.
Given this example:
...
0
votes
1answer
123 views
Need algorithm to take “max” of scores, but with “quality” weighting
I have an application where I get a small number of scores from medical tests (the same test repeated a few times) and I need to combine them. Normally the highest score would "win" in this ...
1
vote
2answers
126 views
from weighted average to single values
think about when you're computing a weighted average: you do something like
W = sum(amount*weight) / sum(weight)
Now I need to find every amount (amount0, amount1.....) starting from knowing the ...
1
vote
2answers
77 views
Maximum Profit at which combination
A dealer deals only in colour TVs and VCRs . He wants to spend up to Rs.12 lakhs to buy 100 pieces. He can purchase colour TV at Rs. 10,000 and a VCR at Rs. 15,000. He can sell a colour TV at Rs. ...
5
votes
2answers
310 views
How many decimal places are needed for incremental average calculation?
If using the following formula to incrementally calculate average value:
$$m_n = m_{n-1} + \frac{a_{n}-m_{n-1}}{n}$$
And the number of decimal places to where you can save $m_n$ is limited to $d$ ...
0
votes
1answer
59 views
Algorithm to Get a Product score based on rating
I am trying to device a algo for product score. Here are the inputs
User rates a product on 5 different criteria out of 10
Each criteria has a different weightage with all adding up to 100%
There ...
0
votes
1answer
276 views
Calculating Average Percent
I have two ways to calculate the average starting price of an auction item compared to it's actual value.
...
1
vote
0answers
42 views
Taking averages
Suppose I have a function $f(\theta)$ that is a function of the angle $\theta\in [0,2\pi)$.
Why is the average of $f$ over a large collection of randomly oriented objects:
$$\int f(\theta)\sin ...
1
vote
1answer
97 views
Error Metric which incorporates both mean & standard deviation of data in euclidean space
For simplicities sake (the actually problem is more complex)...Let say I have a set of n 3d points, whose position move over time. For all pairs, I have calculated the mean and standard deviation of ...
2
votes
2answers
60 views
Calculating statistic for multiple runs
I have s imple, general question regarding calculating statistic for N runs of the same experiment. Suppose I would like to calculate mean of values returned by some Test. Each run of the test ...
1
vote
0answers
21 views
Dynamic Light Scattering
In DLS does the combination of the Time Average and Ensemble Average give a better statistical average than the results shown by each case considered separately ?
1
vote
1answer
85 views
Fréchet mean between points in $\mathbb{R}^3$
Let $X$ be a set of $n$ points in $\mathbb{R}^3$ and $f_m$ be the Fréchet mean, i.e.:
$$
f_m= \arg \min_{p \in M} \sum_{i=1}^n w_id^2(p,x_i)
$$
where $(\mathbb{R}^3,d)$ is a complete metric space, ...
0
votes
0answers
24 views
How do I smoothen / average the withdrawal percent?
I need help with finding an appropriate formula to use in this scenario. I am trying to solve the famous 4 percent withdrawal problem. Here's the problem statement:
On a form, user enters his ...
1
vote
1answer
82 views
How long does it take to complete a sticker album?
We are collecing stickers in chocolate bars and whenever we open a bar we get a random new sticker. There are many different stickers and we try to collect them all.
We open the first bar and get a ...
2
votes
0answers
62 views
How can you calculate actual values when all you have is rolling averages?
Let's say you have a set of data that is rolling 6 month averages of the actual monthly data. Good data collection would mean you saved the actual values and then calculated the rolling averages, but ...
1
vote
2answers
52 views
Constructing an average equation - Standardized Test
A question in the standardized test is:
The average of $n$ numbers is $a$. If $x$ is subtracted from each number the average will be
a) $(ax)/n\quad$ b) $(an)/x\quad$ c) $an-x\quad$ d) ...
0
votes
1answer
36 views
Which of the following cannot possibly be the average - Standardized Test
I came across a question while preparing for a standardized test that is kind of confusing. Hope you guys could help me out here.
The question is:
Three men have weights that range from 110 to 135 ...
0
votes
1answer
86 views
Calculating average of word problem
I was preparing for a standardized test and came across the following problem:
During a closeout sale 30 suits are sold at \$60 each.The price is the reduced to \$50 each and 20 suits are sold. At ...
2
votes
3answers
78 views
Problem with calculating average.
I came across the following question.
A man travels a distance of $20$ miles at $60$ miles/hr and then return over the same route at $40$ miles/hr. What is the average rate for the round trip in ...
0
votes
1answer
655 views
Weighted average vs. weighted mean
Is there a formal difference between weighted average and weighted mean?
I get corrected to the latter if I type in the former in wikipedia, and then there is a lot of stuff about the name "average" ...
1
vote
1answer
87 views
Determining the error from a list of individual errors
I have a list of values each with a corresponding error. I can determine the average/mean of the list, but I'm not sure how to best calculate the error over the entire population.
e.g.
...
0
votes
2answers
303 views
Weighted average of two frequencies
This should be really simple but I'm getting stuck and I'm probably extremely dumb..
I know that a machine receives two kind of parts:
Type 1 -> with frequency 50 per week, each one is processed for ...
2
votes
1answer
157 views
Remove statistical outliers
I've analysed newspapers by counting the language distributions of the articles.
The results look like that:
...
3
votes
1answer
207 views
Average sine of an angle between two rays in a cone
I'm looking for an average value of sine of an angle between two rays, lying within a cone with a certain angle.
Given a cone with an aperture of ${2\chi}$ and two rays lying within the cone. The ...
1
vote
4answers
176 views
Fastest Method to solve this average problem
average of A and B is 71; of B and C is 76; of A and C is 79.
How to find the average of A,B,C.
I know the way of solving this problem using equations.But it takes time.So wanted to know if any other ...
2
votes
0answers
122 views
Average transformation matrix?
I have several estimates of the transformation matrix between two planes and some values that give some indication of the error involved in the estimate.
How can I use this information to gain the ...
2
votes
1answer
161 views
Calculating kWh from multiple watt readings
I have a file which contains watt readings for various times throughout the day. A reading is stored roughly every 6 seconds.
...
2
votes
2answers
746 views
Finding percentile rank without knowledge of distribution
Say you take a test and are told your individual score, as a percentage. Eg: 95%.
You are also told the aggregate score (average) of all students together, as well as how many students in total took ...
2
votes
2answers
543 views
Average distance between two points in a circular disk
How can I find an average distance between two points lying inside a circular disk of a certain radius?
I wonder if there is any other way except of using a Monte Carlo method?
4
votes
2answers
509 views
Real world examples for Mode in Statistics
I am looking for some real world examples for mode in Statistics involving topics which students like say Football or Social networks. Also they need to clearly identify differences in the usefulness ...
0
votes
1answer
218 views
Error propagation and averages, a practical question
Ok, I'm sure this is simple, yet I'm confused.
Lets say my goal is to obtain an average concentration C=N/V so I take a number of N and V readings with errors:
$N_1=50\pm2, V_1=100\pm4$
...
3
votes
2answers
395 views
What do curly brackets mean in this formula?
In this paper, in the Formula at the beginning of 2.2, we have
$B=\{b_i(O_t)\}$
where
$i=0,1$ - the number of probability formula
$O_t$ - the state at moment $t$
$b_i(O_t)$ - two probabilities ...
1
vote
4answers
221 views
Get `n` random values between 2 numbers having average `x`
I want to get n random numbers(e.g n=16)(whole numbers) between 1 to 5(including both) so that average is x.
x can be any value between (1, 1.5, 2, 2.5, 3, 3.5, 4, ...
1
vote
1answer
85 views
Is the average of all $x$ such that $0 \le x \le 1$ $ \forall $ $x \in \mathbb{R}$ equal to $\frac{1}{2}$?
Is the average of all $x$ such that $0 \le x \le 1$ $ \forall $ $x \in \mathbb{R}$ equal to $\frac{1}{2}$ ?
It may seem this way but how can we show that indeed it is $\frac{1}{2}$. We know that the ...
-1
votes
1answer
692 views
Normalizing a matrix using matrix operations
I need some help in normalizing my matrix. I have a 5X4 matrix A. I want to normalize each column. Following is the explanation on the operations
B = Operation of matrix (A)
B matrix is 5x4 matrix. ...
