The average of six results is 15 and that of the first five is 13. The sixth result is?\nOptions:\n(A) 20\n(B) 25\n(C) 15\n(D) 22\n(E) 18
Think hard. Detailed solution:
(B)
6 * 15 â€“ 5 * 13 = 25.

Thus, the answer is (B)