Series – Railway Reasoning part – 7

Total Questions: 50

1. 1, 5, 29, ? [RRB NTPC 07/01/2021 (Evening)]

Correct Answer: (b) 259
Solution:

1¹ + 0 = 1
2² + 1 = 5
3³ + 2 = 29
So next term
4⁴ + 3 = 259

2. ABF, BCG, CDH, DEI, EFJ, ? [RRB NTPC 08/01/2021 (Morning)]

Correct Answer: (d) FGK
Solution:

1st alphabet + 1 = 1st alphabet of the next letter-cluster.
2nd alphabet + 1 = 2nd alphabet of the next letter-cluster.
3rd alphabet + 1 = 3rd alphabet of the next letter-cluster.
Next letter-cluster → E + 1 = F, F + 1 = G, J + 1 = K. So, FGK

3. 3, 11, 27, 59, ? [RRB NTPC 08/01/2021 (Morning)]

Correct Answer: (d) 123
Solution:

4. CKV, DLW, EMX, ? [RRB NTPC 08/01/2021 (Evening)]

Correct Answer: (a) FNY
Solution:

5. 9, 81, 6561, ? [RRB NTPC 08/01/2021 (Evening)]

Correct Answer: (d) 43046721
Solution:

Logic:- the next number is the square of the previous number.

6. 3, E, 8, L, ? [RRB NTPC 09/01/2021 (Morning)]

Correct Answer: (a) 17
Solution:

7. Find the missing letter/series to complete the following sequence: [RRB NTPC 09/01/2021 (Morning)]

Correct Answer: (a) 7/4
Solution:

The series is an alternate series of,

8. Select the combination of letters that when sequentially placed in the blanks will create a repetitive patterns. [RRB NTPC 09/01/2021 (Morning)]

c _ bca _ c _ bc _ b

Correct Answer: (a) abaa
Solution:

We can write the above as c_b / ca_ / c_b / c_b
So, the correct sequence will be, c a b ca b c a b c a b i.e. abaa

9. 37, 21, 13, 9, ? [RRB NTPC 09/01/2021 (Morning)]

Correct Answer: (a) 7
Solution:

37 - 21 = 16,
21 - 13 = 8,
13 - 9 = 4 ,
In the above series the difference between the consecutive numbers is decreasing by half of it.
So the fifth term will be = (9 - 2) = 7

10. G7R18, H8S19, I9T20, ? [RRB NTPC 09/01/2021 (Evening)]

Correct Answer: (a) J10U21
Solution:

The logic is the alphabet and their position and in the next cluster next alphabet and then their position is written.