Three of the following four triads are alike in a certain way as they are formed by performing same mathematical operations among themselves and thus form a group. Which triad does NOT belong to that group?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 5 : 10 : 126.
The logic followed is:
Logic: First no. : First no. × 2 : First no.3 - 1
Now, checking all the options:
Option (1): 9 : 18 : 728 →
⇒ 9 : 9 × 2 : (9)3 - 1
⇒ 9 : 18 : (729 - 1) = 9 : 18 : 728
Option (2) 6 : 12 : 215 →
⇒ 6 : 6 × 2 : (6)3 - 1
⇒ 6 : 12 : (216 - 1) = 6 : 12 : 215
Option (3) 2 : 4 : 7 →
⇒ 2 : 2 × 2 : (2)3 - 1
⇒ 2 : 4 : (8 - 1) = 2 : 4 : 7
Option (4) 5 : 10 : 126 →
⇒ 5 : 5 × 2 : (5)3 + 1
⇒ 5 : 10 : (125 - 1) = 5 : 10 : 124 ≠ 126
Here, '5 : 10 : 126' does not belong to group as it does not follows the logic.
Hence, 5 : 10 : 126 is the correct answer.