Question : Directions: Three of the following four triads are alike in a certain way as they are formed by performing the same mathematical operations among themselves and thus form a group. Which triad does not belong to that group?
Option 1: 11 : 21 : 121
Option 2: 2 : 3 : 4
Option 3: 7 : 15 : 49
Option 4: 9 : 17 : 81
Correct Answer: 7 : 15 : 49
Solution :
Let's check the given options –
First option:
(11 : 21 : 121)→11 + (11 – 1) = 11 + 10 = 21; 11
2
= 121
Second option:
(2 : 3 : 4)→2 + (2 – 1) = 2 + 1 = 3; 2
2
= 4
Third option:
(7 : 15 : 49)→7 + (7 – 1) = 7 + 6 = 13 ≠ 15; 7
2
= 49
Fourth option:
(9 : 17 : 81)→9 + (9 – 1) = 9 + 8 = 17; 9
2
= 81
Therefore, only the third option does not follow the pattern of the others. Hence, the third option is correct.
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