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
2. 1200, 480, 192, 76.8, 30.72, (?)
(a) 15.91
(b) 18.321
(c) 12.288
(d) 12.234
(e) None of these
3. 13, 14, 30, 93, 376, (?)
(a) 1848
(b) 1125
(c) 1150
(d) 1885
(e) None of these
4. 505, 528, 574, 643, 735, (?)
(a) 850
(b) 888
(c) 812
(d) 618
(e) None of these
5. 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
7. 888, 440, 216, 104, 48, 22, 6
(a) 440
(b) 216
(c) 104
(d) 48
(e) 22
8. 2, 3, 6, 15, 52.5, 157.5, 630
(a) 3
(b) 6
(c) 15
(d) 52.5
(e) 157.5
9. 5, 8, 20, 42, 124, 246, 736
(a) 8
(b) 20
(c) 42
(d) 124
(e) 246
10. 1050, 510, 242, 106, 46, 16, 3
(a) 510
(b) 242
(c) 106
(d) 46
(e) 16
ANSWER WITH EXPLANATION:
1. (d):
5, 9, 18, 34, 59, 95 (144)
+4 +9 +16 +25 +36 +49
2. (c)
1200*2/5 , 480*2/5, 192*2/5, 76.8*2/5, 30.72*2/5,(12.288)
3. (d)
13, 14, 30, 93, 376, (1885)
*1+1 *2+2 *3+3 *4+4 *5+5
4. (a)
505, 528, 574, 643, 735, (850)
+23 +46 +69 +92 +115
5. (a)
13, 16, 14, 17, 15, 18, (16)
+3 -2 +3 -2 +3 -2
6. (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
7. (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
8. (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
9. (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
10. (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