# 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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### Linear regression to compare proportions in different groups...?

Days ago I asked this question (Comparing proportions inside groups...?) and someone told me to compute a linear regression over each frequency distribution and compare the average residuals to see ...
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### proof of a relationship related to half-normal distribution [duplicate]

Would anyone be able to help solve this: $\dfrac{\mathbb E[|X-\mu|]}{\sqrt{\mathbb E[(X-\mu)^2]}}=\sqrt{\frac2\pi}$ for a normal distribution. Related to the mean of a half-normal distribution?
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### relationship between arithmetic mean and standard deviation in a normal distribution [closed]

I know that Sa divided by Sq (arithmetic mean/standard deviation) on a standard normal distribution is equal to 2/(2pi)^0.5 or 0.7978 but need to have the mathematical solution. Can anyone help me ...
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### Reinforcement learning with simple integer arithmetic actions

Motivated by an experimental investigation in pure mathematics, I am interested in the following type of reinforcement learning problems: The state is a collection of N integers, where there are no ...
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### In mathematics, what is coefficient if variable is not having any coefficient in percentage equation?

If I am having equation as X-14.8%X = 5.98, then what is coefficient of variable X? Is it 1% or 100%?
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### How to compare the mean to the mean of mean values of dummy variables?

I am trying to validate the calculations of a mean value for a collection of binary variable values. The validation process is where I compare x to y where: x is the mean value of percentage of ...
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### "Values not normally distributed, so were transformed to log10 values before" - how to read the results?

I have been researching a medical topic and stumbled upon a paper that is really useful for me but I am limited by my math/statistics knowledge. The paper reads as follows: the Gmax and Tlag ...
1k views

### How to find median value for five given elements based on the max min and sum of the elements

this question occurred in my interview, How to find the median values using the min, max, and sum values of the given 5 elements? for eg if given 3 elements we can use sum - min - max a = [3,6,9] here ...
589 views

### Difference between the terms "Frequency" and "Abundance"

How does Abundance or Relative abundance (Chemistry) differs from statistical frequency? Or it is just another term for statistical frequency in context of chemistry? Update: here are some example ...
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### How to determine the total vaccinated citizens given the number of 1st and 2nd dose administered? [closed]

Currently, there are 80,918 first COVID-19 vaccine doses and 52,949 vaccines that have been administered in my city. I am interested in looking at the total citizens who are either fully vaccinated or ...
59 views

### Correctly averaging grades when tests are over different points

Suppose in a school the grading system is from $60,$ and you've done $3$ tests, $1$ over $60,$ and the other two were smaller tests over $40$ and $20$ points respectively. I am trying to learn what ...
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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!
307 views

### 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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### 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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1k views

### 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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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 ...