Series – Railway Reasoning part

21. Select the letter-cluster that does NOT belong to the given series. [RRB NTPC 23/01/2021 (Morning)]

CDE, FGH, IJK, LNM

(a) CDE
(b) FGH
(c) LNM
(d) IJK

Correct Answer: (c) LNM

Solution:

Three consecutive letters are written in sequence But in LNM, M should be before N

22. 1O5, 1P6, 1Q7, ? [RRB NTPC 23/01/2021 (Evening)]

(a) 1R8
(b) R18
(c) 81R
(d) 8R1

Correct Answer: (a) 1R8

Solution:

Logic - the letter is written in between the place value of the letter. And the alphabet is in increasing order.
Next will be R, place value = 18 ⇒ 1 𝑅 8

23. 6, 25, 62, ?, 214 [RRB NTPC 23/01/2021 (Evening)]

(a) 123
(b) 124
(c) 115
(d) 100

Correct Answer: (a) 123

Solution:

2³ − 2 = 6
3³ − 2 = 25 ,
4³ − 2 = 62
5³ − 2 = 123

24. 20, 40, 63, 90, 122, ? [RRB NTPC 23/01/2021 (Evening)]

(a) 120
(b) 150
(c) 160
(d) 110

Correct Answer: (c) 160

Solution:

25. - 4, - 3, - 1, 2, 6, ? [RRB NTPC 25/01/2021 (Morning)]

(a) 11
(b) 15
(c) 10
(d) 12

Correct Answer: (a) 11

Solution:

26. 1, 2, 6, 24, 120, ? [RRB NTPC 25/01/2021 (Morning)]

(a) 96
(b) 600
(c) 720
(d) 144

Correct Answer: (c) 720

Solution:

27. DPX, EQY, FRZ, GSA, ? [RRB NTPC 25/01/2021 (Evening)]

(a) ND
(b) NE
(c) NJ
(d) NF

Correct Answer: (b) NE

Solution:

28. DPX, EQY, FRZ, GSA, ? [RRB NTPC 27/01/2021 (Morning)]

(a) BTH
(b) HUB
(c) HTB
(d) BHU

Correct Answer: (c) HTB

Solution:

DPX, EQY, FRZ, GSA, HTB
D + 1= E, E + 1 = F, F + 1= G, G + 1 = H
P + 1= Q, Q + 1 = R, R + 1= S, S + 1 = T
X + 1= Y, Y + 1 = Z, Z + 1= A, A + 1 = B