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 second number of the new series?
-
5, 4, 9, 18, 66, 195
-
- 12
- 25
- 20
- 18
- None of these
Correct Option: D
This series is made of two position series .
Even Position series :-
∴ First term = 5
Second term = ( First term × 1 ) - 1
⇒ Second term = ( 5 × 1 ) - 1 = 4
Fourth term = ( Third term × 2 ) - 2
⇒ Fourth term = ( 9 × 2 ) - 2 = 18 , 16 should be Fourth term because ( 9 × 2 ) - 2 = 16 .
So 18 is wrong. we get 16 as Fourth term.
Sixth term = ( Fifth term × 3 ) - 3
⇒ Sixth term = ( 66 × 3 ) - 3 = 195
Odd Position series -
∴ Second term = 4
Third term = ( Second term × 2 ) + 2
⇒ Third term = ( 4 × 2 ) + 2 = 10
Fifth term = ( Fourth term × 3 ) + 3
⇒ Fifth term = ( 16 × 3 ) + 3 = 51
