## Averages

The average (arithmetic mean) of the weights of 26 stones is p pounds. In terms of p, what is the total weight of the stones, in pounds?

A. 26 + p

B. p - 26

C. p / 26

D. 26 / p

E. 26p

## Knowsys Method

**Read the problem carefully.** Be sure to keep the numbers in this problem straight so that you do not make any careless mistakes in your work.

**Identify the bottom line. ** total weight of the 26 stones = ?

**Assess your options. **You could pick a number for p and then use it to find the total weight or you could leave p as a variable. Either way, you need to use the "average formula," which you should definitely memorize. Every time you see the word "average" on the exam, you should immediately think: "average = the sum divided by the number." Let's use that formula to solve this problem quickly and easily.

**The Average Formula**

**Attack the problem.**

We are looking for the "total weight," which is the same thing as the SUM. So, let's rearrange to get:

**average * number = sum **

In this particular problem we know the average = p and the number = 26. Let's just plug in to get:

p(26) = sum

26p = sum

**Loop back. **Verify that you solved for the bottom line.

The correct answer is E.

**Level = Medium **

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