What is the average (arithmetic mean) of all multiples of 10 from 10 to 300 inclusive?	Answers:	A) 155	B) 195	C) 200	D) 205	E) 210

Rationale: "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 300 , inclusive . to start , we can figure out the total number of terms rather easily : 1 ( 10 ) = 10 2 ( 10 ) = 20 . . . 30 ( 10 ) = 300 so we know that there are 30 total numbers . we can now figure out the sum of those numbers with ' bunching ' : 10 + 300 = 310 20 + 290 = 310 30 + 280 = 310 etc . since there are 30 total terms , this pattern will create 15 ' pairs ' of 310 . thus , since the average = ( sum of terms ) / ( number of terms ) , we have . . . ( 15 ) ( 310 ) / ( 30 ) = 155 answer : a"
Answer: A