Direction: In each of the following questions, a number series is given in which one number is wrong. You have to find out that number and have to follow the new series which will be started by that number. By following this, which will be the 2nd number of the new series?
-
2 , 9 , 5 , 36 , 125 , 648 , 3861
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- 12
- 11
- 75
- 72
- None of these
Correct Option: E
As per the details in the question the series is in the form of
First term = 2
Second term = First term × 1 + 7
⇒ Second term = 2 × 1 + 7 = 2 + 7 = 9 ;
Third term = Second term × 2 - 11
⇒ Third term = 9 × 2 - 11 = 18 - 11 = 5; 5 is wrong. It should be 7 as Third term .
Similarly , we can find all others terms also.
Fourth term = Third term × 3 + 15
⇒ Fourth term = 7 × 3 + 15 = 21 + 15 = 36 ;
Fifth term = Fourth term × 4 - 19
⇒ Fifth term = 36 × 4 - 19 = 144 -19 = 125 ;
Sixth term = Fifth term × 5 + 23
⇒ Sixth term = 125 × 5 + 23 = 625 + 23 = 648 ;
Seventh term = Sixth term × 6 - 27
⇒ Seventh term = 648 × 6 - 27 = 3888 - 27 = 3861 .
New series is
First term = 5 × 1 + 7 = 12;
Second term = 12 × 2 - 11 = 13.
Hence Second term of new series is 13 and correct option is ( E ) .
