Number series : 10 Questions from Previous Exams

number series

Ques 1.

5 , 15 , 30 , 135, 405, 1215, 3645
(a) 3645
(b) 5
(c) 405
(d) 1215
(e) 30

Ques 2.

2, 3, 6, 10, 18, 27, 54
(a) 10
(b) 27
(c) 3
(d) 6
(e) 18

Ques 3.

3 , 4 , 8 , 17 , 33 , 49 , 94
(a) 17
(b) 8
(c) 4
(d) 33
(e) 49

Ques 4.

36 , 49 , 100 , 144 , 196 , 256 , 324
(a) 256
(b) 36
(c) 49
(d) 144
(e) 100

Ques 5.

508 , 250 , 124 , 60 , 28 , 12 , 4
(a) 28
(b) 124
(c) 60
(d) 12
(e)250

Ques 6.

2 , 3 , 5 , 8 , 15 , 21 , 34 , 55
(a)5
(b) 8
(c)3
(d)21
(d)15

Ques 7.

2 , 5 , 10 , 18 , 26 , 37 , 50 
(a) 37
(b) 18
(c) 5
(d) 50
(e)2

Ques 8.

1 , 4 , 7 , 11 , 16 , 22 , 29
(a) 4
(b) 11
(c)22
(d)29
(e)1

Ques 9.

4 , 6 , 9, 18 , 34 , 59 , 95
(a) 34
(b) 6
(c) 18
(d) 95
(e)9

Ques 10.

54  , 43 , 34 , 26 , 22 , 19 , 18
(a) 26
(b) 18
(c) 43
(d) 22
(e) 34

solutions :

Ans 1. Each  term of the  series  is obtained by  multiplying the previous  term by 3 . 

⟹ Therefore the particular  order is  5, ( 5 x 3 = 15) , ( 15 x 3 = 45) , ( 45 x 3 = 135 ) , ( 135  x 3  = 405 )  , ( 405 x 3 = 1215 )., ( 1215 x 3 = 3645) , .. and so on . 

⟹ Hence , alternative  (e)  consists  of the wrong term.

Ans 2. In the  given sequence  second term is  1.5  the first , the third  term is 2 times  the second and so on,  Therefore , alternative  (a)  consists  of the wrong  term. 

 Ans 3. In the given sequence  difference between  successive  terms is in the order 12 , 22 , 32 .... . Therefore  58 should  replace 49  to from the series . 

⟹ Hence alternative (e)  consists  of the wrong term.

Ans 4. Terms  of the  series would be 62 , 82 , 102, 122, ...... 182 if 49  is replaced 64 . 

⟹ Therefore  , alternative  (c)  consists  of the wrong term.

Ans 5. If 250  is replaced by 252, then  difference  successive  terms of the series will  be in the order of 256 , 128, 64, 32 , 16 , 8  respectively which from a particular  order . 

⟹ Therefore , alternative (e)  consists  of the wrong term.

Ans 6.  If 15 is replaced  by 13 then a particular  order of terms in the series  will be formed in which  sum of two successive terms  is equal  to the next term.  

⟹ Therefore , alternative (e)  consists  of the wrong term.

Ans 7. If 18 is replaced  by 17  then terms of the series  will be  arranged  in the order of 12+ 1 , 22+ 1, 32 + 1 ....72+ 1 .

⟹ Therefore , alternative(b)  consists  of the wrong term.

Ans 8. If first term of the series is replaced by 2 then difference between successive terms of the series will be in the order of 2 , 3 ,4 ,5 ,6 ,7.

⟹ Therefore , alternative (e) consists of the wrong term.

Ans 9. If 6 is replaced  by 5 then difference  between  successive terms will be in  the order of 1, 4, 9, 16 ,25, 36 .

⟹ Therefore , alternative (b) contain the wrong term.

Ans 10. If  26 is replaced  by 27 , then  difference  between successive terms of the series  will be  on the  order of 11, 9, 7, 5, 3 ,1 .

⟹ Therefore , alternative (a)  consists  the wrong  term of the series.

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