What is the average (arithmetic mean) of all multiples of 10 from 10 to 500 inclusive?  Answers:
A) 190  B) 255  C) 200  D) 205  E) 210
This question can be solved with the Average Formula and 'bunching.'   We're asked for the average of all of the multiples of 10 from 10 to 500, inclusive.   To start, we can figure out the total number of terms rather easily:   1(10) = 10   2(10) = 20   ...   50(10) = 500   So we know that there are 50 total numbers.   We can now figure out the SUM of those numbers with 'bunching':   10 + 500= 
<gadget id="calculator">10 + 500</gadget>
<output>510</output>
510   20 + 490= 
<gadget id="calculator">20 + 490</gadget>
<output>510</output>
510   30 + 480= 
<gadget id="calculator">30 + 480</gadget>
<output>510</output>
510   Etc.   Since there are 50 total terms, this pattern will create 25 'pairs' of 510.   Thus, since the average= (Sum of terms)/(Number of terms), we have...   (25)(510)/(50) =   255   Final Answer:   255
<result>B</result>
What is the average (arithmetic mean) of all multiples of 10 from 10 to 500 inclusive?