The average of 25 results is 18. The average of first 12 of those is 14 and the average of last 12 is 17. What is the 13th result? Answers:	A) 74	B) 75	C) 69	D) 78	E) 45

Rationale: "solution : sum of 1 st 12 results = 12 * 14 sum of last 12 results = 12 * 17 13 th result = x ( let ) now , 12 * 14 + 12 * 17 + x = 25 * 18 or , x = 78 . answer : option d"
Answer: D