What is the average (arithmetic mean) of all multiples of 10 from 10 to 200 inclusive?  Choose the correct choice from the following options.
A) 190 B) 105 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 200, inclusive.   To start, we can figure out the total number of terms rather easily:   1(10) = 10   2(10) = 20   ...   20(10) = 200   So we know that there are 40 total numbers.   We can now figure out the SUM of those numbers with 'bunching':   10 + 200= 
<gadget id="calculator">10 + 200</gadget>
<output>210</output>
210   20 + 190= 
<gadget id="calculator">20 + 190</gadget>
<output>210</output>
210   30 + 180= 
<gadget id="calculator">30 + 180</gadget>
<output>210</output>
210   Etc.   Since there are 20 total terms, this pattern will create 10 'pairs' of 210.   Thus, since the average= (Sum of terms)/(Number of terms), we have...   (10)(210)/(20) =105   Answer : 105
<result>B</result>
What is the average (arithmetic mean) of all multiples of 10 from 10 to 200 inclusive?