# Questions tagged [arithmetic]

For on-topic questions involving arithmetic. Try to include also a more statistical tag. For purely mathematical questions about arithmetic, please use math SE https://math.stackexchange.com/

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### Probability from Chi-Squared distribution

If I have a random variable called $A$ and $A \sim \mathcal{N}(0,1)$, how can I get the value of $X$ if $P(X<5A^2<6.52)=0.5310$. It seems that the answer is $2.4109$, but I don't know how to ...
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### Equality of the Covariance of Two Random Variables and the Expected Value of the Product of One and the Difference Between the Other and Its Mean

I am trying to understand the second equality in the attached image. Could you please help me by guiding me as to how I can prove this? Thanks!
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### How can I normalize price history between -1 and 1 while keeping the ratio of price differences to each other the same?

I want to normalize a series of numbers to all be between -1 and 1, but I would like to do it in a way where the relative difference between price elements stays the same, if possible. Example list of ...
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### Deep Learning: Should I dot product (input, weight) or dot(weight, input)? Does it even matters?

I've been following through Neural Networks from Scratch and found that the author switches the order of dot(input, weight) from time to time. The calculation shows that the dot product gives ...
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### How to calculate $\Delta Y$ given $\Delta X$, a simple linear equation, and a correlation score?

Suppose I conduct a correlation and SLR analysis on a bivariate data set and obtain the following: $$r=.63$$ $$Y=2.1+5.6X$$ If I increase X by 300, how much will Y go up?
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### What is the expected value and variance of the arithmetic mean

How can I calculate the expected value and variance of the arithmetic mean? I know that is the arithmetic mean, but how do I use this to figure out the expected value?
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### Expected value homework question

Im not sure why the expected value that I got is incorrect. The method that I did is: (0)(0.568)+(7)(0.101)+(11)(0.218)+(9)(0.113)
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### What mean should I use when few big values? [duplicate]

for a project I need to calculate several means, I then compare each of these means to a distribution under the null hypothesis H0. However sometimes some values (...
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### What is the underlying math needed to answer the following questions:

Some background: I was applying for an entry level business analyst position, and I was completely lost with some of these questions. These questions were from the practice test. I'm not sure how I ...
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### Converting annual to daily mortality rate

In one excel workbook I am working on right now, the annual mortality rate is given as 3.082% And the formula for calculating the daily mortality rate is 1-EXP(LN(1-[annual mortality rate]/365) Why ...
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### Is it better to take a mean of means or a grand mean when relaying rate data?

I am working with a dataset that includes number of fish caught in a day, and number of hours spent fishing that day. The variable of interest (outside of general summary statistics) is the number of ...
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### How does this manipulation of summation of exponents work?

I found this paper by Fischer and Igel (2012) (1). I am not able to get past this last step in their derivations (eqn 22, p24) where $h_i$ are values of $h$. Can anyone tell me how they reduced the ...
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### Sufficient Statistic for inverse Gaussian Distribution

Let $X_1,...,X_n$ be a random sample from population with the pdf of the inverse Gaussian distribution f(x|\theta,\beta)=(\frac{\beta}{2 \pi x^3})^\frac{1}{2}e^{-\frac{\beta(x-\theta)^2}{2\...