The average of 13 result is 20. Average of the first 8 of them is 20 and that of the last 8 is 40. Find the 8th result?
Options:
(A) 35
(B) 37
(C) 46
(D) 90
(E) 100 Let's think first. Stream of consciousness:
Sum of all the 13 results = 13 * 20 = 260
Sum of the first 7 of them = 8 * 20 = 160
Sum of the last 7 of them = 8 * 40 = 320
So, the 8th number = 260 + 160 - 320 = 100.
So, the answer is (E).