Number Series

Directions (1 – 5): What will come in place of the (?) in the following number series?
1. 5, 9, 18, 34, 59, 95, (?)
(a) 272
(b) 186
(c) 140
(d) 144
(e) None of these

  1. 1200, 480, 192, 76.8, 30.72, (?)
    (a) 15.91
    (b) 18.321
    (c) 12.288
    (d) 12.234
    (e) None of these
  2. 13, 14, 30, 93, 376, (?)
    (a) 1848
    (b) 1125
    (c) 1150
    (d) 1885
    (e) None of these
  3. 505, 528, 574, 643, 735, (?)
    (a) 850
    (b) 888
    (c) 812
    (d) 618
    (e) None of these
  4. 13, 16, 14, 17, 15, 18, (?)
    (a) 16
    (b) 15
    (c) 14
    (d) 21
    (e) None of these

Directions (6-10): Find the wrong one in the series
6. 4, 5, 15, 49, 201, 1011, 6073
(a) 5
(b) 15
(c) 49
(d) 201
(e) 1011

  1. 888, 440, 216, 104, 48, 22, 6
    (a) 440
    (b) 216
    (c) 104
    (d) 48
    (e) 22
  2. 2, 3, 6, 15, 52.5, 157.5, 630
    (a) 3
    (b) 6
    (c) 15
    (d) 52.5
    (e) 157.5
  3. 5, 8, 20, 42, 124, 246, 736
    (a) 8
    (b) 20
    (c) 42
    (d) 124
    (e) 246
  4. 1050, 510, 242, 106, 46, 16, 3
    (a) 510
    (b) 242
    (c) 106
    (d) 46
    (e) 16

ANSWER WITH EXPLANATION:

(d):
5, 9, 18, 34, 59, 95 (144)

+4 +9 +16 +25 +36 +49

(c)
1200*2/5 , 480*2/5, 192*2/5, 76.8*2/5, 30.72*2/5,(12.288)

(d)
13, 14, 30, 93, 376, (1885)

*1+1 *2+2 *3+3 *4+4 *5+5

(a)
505, 528, 574, 643, 735, (850)

+23 +46 +69 +92 +115

(a)
13, 16, 14, 17, 15, 18, (16)

+3 -2 +3 -2 +3 -2

(a)
2nd term = (1st term *1+2)= (4*1+2) = 6

3rd term = (2nd term*2+3) = (6*2+3) = 15

4th term = (3rd term*3+4) = (15*3+4) = 49

5th term = (4th term*4+5) = (49*4+5) = 210 and so on

Therefore 5 is wrong

(e)
2nd term = (1st term – 8)/2 = (888-8)/2 = 440

3rd term = (2st term – 8)/2 = (440-8)/2 = 216

4rd term = (3st term – 8)/2 = (216-8)/2 = 104

5rd term = (4st term – 8)/2 = (104-8)/2 = 48

6rd term = (5st term – 8)/2 = (48-8)/2 =20

Therefore 22 is wrong

(d)
2nd term = (1st term* 1.5) = 2 * 1.5 = 3

3rd term = (2st term* 2) = 3* 2 = 6

4th term = (3st term* 2.5) = 6 * 2.5 = 15

5th term = (4st term* 3) = 15 * 3 = 45

Therefore 52.5 is wrong

(b)
2nd term = (1st term * 2 – 2) = (5 * 2 – 2) = 8

3rd term = (2st term * 3 – 2 ) = (8* 3 – 2) = 22

4th term = (3st term * 2 – 2 ) = (22 * 2 – 2) = 42

5th term = (4st term * 3 – 3) = (42 * 3 – 2) = 124 and so on

Therefore 20 is wrong

  1. (c)
    2nd term = (1st term – 30)/2= (1050-30)/2= 510

3rd term = (2st term – 26)/2= (510-26)/2= 242

4th term = (3st term – 22)/2 = (242-22)/2 = 110

Therefore 106 is wrong