Alissa Fong

**MA, Stanford University**

Teaching in the San Francisco Bay Area

Alissa is currently a teacher in the San Francisco Bay Area and Brightstorm users love her clear, concise explanations of tough concepts

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We have **rational functions** whenever we have a fraction that has a polynomial in the numerator and/or in the denominator. An excluded value in the function is any value of the variable that would make the denominator equal to zero. To find the domain, list all the values of the variable that, when substituted, would result in a zero in the denominator.

A lot of times your Math class might start out with a mini unit on statistics. And even though you might not use these skills throughout your Math class this year, these statistics problems often show up on standardized tests, if you have a high school exit exam it'll probably be there or if you're looking ahead to your future thinking about the SAT and ACT these guys show up all over that. So it's important to start building your statistics tool bag now.

The first thing you probably already know and that's the study of mean or average. It's kind of the same idea but we have two different names for it mean or average. In statistics you're going to see the word mean. The way you calculate a mean is to add up all your items remember mean, sum mean add them up after you've done that you divide by the number of items.

This is how your school is going to calculate your GPA, GPA on your report cards stands for grade point average it comes from taking all of your letter grades assigning numbers to them dividing how many classes that you're taking. So this is really is applicable in the real world and it's not too hard once you remember this formula. Again the formula for mean or average you probably already know it, is to sum or add together all of your items and then divide by how many items there are in your set.