Test the following CSS code:

<style type = "text/css">
p.standout{font-size: 24pt; color:blue;background-color:red};
</style>

<p class = "standout">
To really make it stand out, use a red background
</p>

What background color do you see when displayed by IE? How about Firebox? Explain why.

I tried on both IE and Firefox, they both look the same. Perhaps the difference is version specific.

To test the CSS code, you can simply create an HTML file and include the provided code inside the `<style>` tags. Here's an example of how the code can be tested:

First, create an HTML file (e.g., "test.html") and open it using a text editor. Then, copy and paste the provided CSS code and the HTML code into the file:

```
<!DOCTYPE html>
<html>
<head>
<style type="text/css">
p.standout{
font-size: 24pt;
color: blue;
background-color: red;
}
</style>
</head>
<body>

<p class="standout">
To really make it stand out, use a red background
</p>

</body>
</html>
```
Then, save the file. To test the CSS code, simply open the HTML file in different browsers such as Internet Explorer (IE) and Firefox.

Now, to answer your question:

In Internet Explorer (IE), you would see a blue text color applied to the paragraph `<p>` element with class "standout," as specified in the CSS code. However, the red background color may not be applied correctly due to an error in the CSS code.

The error in the CSS code is the semicolon after the closing curly brace `}` of the `p.standout` rule. This semicolon should be removed. So, the correct CSS code should be:

```css
p.standout {
font-size: 24pt;
color: blue;
background-color: red;
}
```

On the other hand, in Firefox (or other web browsers that follow the CSS syntax properly), you would see the blue text color with a red background applied to the paragraph `<p>` element, as expected.

In summary, the background color may not be displayed correctly in Internet Explorer due to the syntax error in the CSS code. Firefox and most modern browsers will display the red background correctly.