## Another System of Linear Equations

Often the most difficult part of solving a system of equations problem is writing out the system from a word description. In this FAQ, we look at a complicated sounding problem and form a system of linear equations from the problem.

This FAQ explores how to take a story problem and write it out as a system of linear equations.

## Tables and Excel

Excel comes in handy for creating tables of values for limits. This FAQ contains two PDFs that demonstrate the process of creating a table using a “fill” in Excel.

How Do I Make A Table Of Values In Excel?

This same process may be used to create tables in other types of spreadsheets such as Google Sheets.

## How Do You Compute Conditional Probability From Data?

It easy to confuse conditional probability with probability of an intersection of two event. They are related! The probability of an event A given that event B has occurred is

The vertical bar | means “given” and the event after it is the event that has already occurred.

Let’s look at some data to determine how to find several different probabilities including conditional probability.

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## How Do You Compute the Sample Mean or Variance in a Spreadsheet?

Both Excel and Sheets use the same commands to calculate a sample mean, sample variance, or sample standard deviation. This FAQ demonstrates how to use these commands.

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## Undoing Rates Using A Graph

Often a rate function or derivative is given by data or a graph. If we can find a function for the data, we can take the antiderivative of the function to undo the rate. But what if the rate is given by a graph whose formula is unknown?

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