8:11:15:18:21:22:22:22:22:22:22:
A. 25 18
B. 25 21
C. 25 29
D. 24 21
Answer:C
8:11:15:18:21:22:22:22:22:22:22:
A. 25 18 B. 25 21 C. 25 29 D. 24 21
Explanation: This is an alternate addition series in which a random number, 21, is interpolated as the third number every third number. The addition series alternates between three and four additions. After each number, the number 21 appears.