# How to Calculate Frequency in a Normal Distribution?

• zgochenour
In summary, the conversation is about creating a calculator that can calculate the frequency of values within a given range based on the standard deviation, mean, and frequency at the mean provided by the user. The example given is of a group with a mean weight of 100kg and a standard deviation of 10kg, with 1000 individuals weighing exactly 100kg. The conversation also mentions the importance of considering sensitivity to parameter values and comparing observed frequency to expected frequency in the calculator.
zgochenour
I am trying to create a calculator that let's a user provide the standard deviation, mean, frequency at that mean, and range of values - then the calculator will give the frequency in that value range.

For instance, purely illustrative -- say you know the mean weight for some group is 100kg. They are normally distributed (exactly) around that mean with a standard deviation of 10kg. 1000 of them are 100kg. How many of the group are between 112kg and 116kg.

I hope that makes sense. Thanks for the help. I'm not really sure where to begin.

zgochenour said:
They are normally distributed (exactly) ... 1000 of them are 100kg.

If they are exactly normally distributed then none would be 100kg. Did you mean to say that 1000 of them are in the interval (99.5,100.5) ? Once you work out the probability of this interval you can compare it to that of the other interval to get an idea of the relative expected frequencies.

Some other things to keep in mind for your calculator are sensitivity to parameter values and observed frequency vs expected frequency.

## What is a normal distribution calculator?

A normal distribution calculator is a statistical tool used to calculate probabilities and values associated with a normal distribution. It can be used to find the area under the curve, determine z-scores, and calculate percentiles.

## How does a normal distribution calculator work?

A normal distribution calculator uses a mathematical formula to calculate probabilities and values based on the mean and standard deviation of a normal distribution. It can also use tables or graphs to visualize the distribution and make calculations.

## Why is a normal distribution important?

A normal distribution is important because many natural phenomena and human attributes follow a normal distribution. It is also used as a benchmark for comparing other distributions and making statistical inferences.

## What are the assumptions of a normal distribution calculator?

The assumptions of a normal distribution calculator include a continuous and symmetrical distribution, a mean and standard deviation that fully describe the distribution, and a large sample size (usually at least 30).

## What are some common uses of a normal distribution calculator?

A normal distribution calculator is commonly used in fields such as statistics, economics, psychology, and biology to analyze data and make predictions. It is also used in quality control to determine if a process is within acceptable limits.

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