Direction: In each of these questions a number series is given. Only one number is wrong in each series. You have to find out the wrong number.
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108 , 54 , 36 ,18 , 9 , 6 , 4
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- 54
- 36
- 18
- 9
- 6
Correct Option: D
The given series is in the below pattern,we can see that
Next term = Previous term ÷ n { putting n = 2 and 1.5 alternately }
First term = 108
Second term = First term ÷ 2
⇒ Second term = 108 ÷ 2 = 54 ;
Third term = Second term ÷ 1.5
⇒ Third term = 54 ÷ 1.5 = 36 ;
Third term = Third term ÷ 2
⇒ Fourth term = 36 ÷ 2 = 18 ;
Fifth term = Fourth term ÷ 1.5
⇒ Fifth term = 18 ÷ 1.5 = 9 is wrong. It should be 12.
Sixth term = Fifth term ÷ 2
⇒ Sixth term = 12 ÷ 2 = 6 ;
Seventh term = Sixth term ÷ 1.5
⇒ Seventh term = 8 ÷ 1.5 = 4
Hence, 9 is wrong. It should be 12.
