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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formula for converting a very long number to a fraction

What is the average (arithmetic mean) of 8, 7, 7, 5, 3, 2, and 2? the answer is $4\frac{6}{7}$. The sum of numbers is 34 and when you divide by 7 it's 4.8571428..... How can I get the fraction of ...
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2answers
28 views

Find average speed, given speeds of two legs [closed]

A train runs for $3$ hours at speed of $55~\text{km}/\text{hour}$, for the next $2$ hours it runs at $65~\text{km}/\text{hour}$. Find the average speed of the train for a $5$ hour journey?
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1answer
46 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
72 views

Moving averages and crossovers in stock markets?

Suppose I take a two moving averages to analyse stock market prices - one $200$ day moving average, $m_{200}$, and another $50$ day moving average, $m_{50}$. How do you decide when to sell and when ...
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1answer
589 views

Calculating a 5 star rating with a reputation number… [duplicate]

Possible Duplicate: 5 star ratings. Bayesian or Weighted average? Similar question, but unlike that question this deals with two factors the stars and reputation. Lets say Stack Exchange ...
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1answer
2k 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. ...
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1answer
196 views

Applying fuzzy logic to determine the degree to which a project is complete

I have a Project made up of tasks. Each task has an estimated completion percentage. I realise I could treat each tasks completion percentage as a representation of the degree of membership to the ...
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1answer
2k views

Can weighted average be used to calculate percentage increase? [duplicate]

Possible Duplicate: Is this a weighted average/percentage problem? Let's say a Marketing company has a total turnover of 10000 \$ There are 3 salesmen A,B,C with the following turnovers: ...
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1answer
43 views

Dropping the lowest number in a set lowers the mean average of the set.

So a friend of mine had her grade drop because her teacher had decided to drop the lowest grade. Is this possible or did the teacher mess up something? And if so, then how is it possible. We've ...
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2answers
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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.