What is the average (arithmetic mean) of all multiples of 10 from 10 to 400 inclusive?
Choose the most appropriate option:	A) 190	B) 195	C) 200	D) 205	E) 210
We're asked for the average of all of the multiples of 10 from 10 to 400, inclusive.   To start, we can figure out the total number of terms rather easily:   1(10) = 10   2(10) = 20   ...   40(10) = 400   So we know that there are 40 total numbers.   We can now figure out the SUM of those numbers with 'bunching':   10 + 400= 
<gadget id="calculator">10 + 400</gadget>
<output>410</output>
410   20 + 390= 
<gadget id="calculator">20 + 390</gadget>
<output>410</output>
410   30 + 380= 
<gadget id="calculator">30 + 380</gadget>
<output>410</output>
410   Etc.   Since there are 40 total terms, this pattern will create 20 'pairs' of 410.   Thus, since the average= (Sum of terms)/(Number of terms), we have...   (20)(410)/(40) =   410/2= 
<gadget id="calculator">410/2</gadget>
<output>205</output>
205   Final Answer:205
<result>D</result>
What is the average (arithmetic mean) of all multiples of 10 from 10 to 400 inclusive?