Series – Railway Reasoning part – 7

Total Questions: 50

41. 1, 1, 3, 5, 11, 21, 43, ? [RRB NTPC 17/01/2021 (Evening)]

Correct Answer: (c) 85
Solution:

42. z1, x4, v9, t16, ? [RRB NTPC 18/01/2021 (Morning)]

Correct Answer: (d) r25
Solution:

In the given series, the letter is decreasing by 2 and the number is a square of consecutive natural numbers.
z - 2 = x, x - 2 = v, v - 2 = t, t - 2 = r
1² = 1 , 2² = 4 , 3² = 9 , 4² = 16 , 5² = 25
So, the next term will be : r25 .

43. 8, 17, 35, 71, ? [RRB NTPC 18/01/2021 (Morning)]

Correct Answer: (c) 143
Solution:

44. ab, cc, ed, ge, ? [RRB NTPC 18/01/2021 (Morning)]

Correct Answer: (c) if
Solution:

45. 0, 6, 20, 42, ? [RRB NTPC 18/01/2021 (Morning)]

Correct Answer: (d) 72
Solution:

46. Z, V, R, ?, J, F [RRB NTPC 18/01/2021 (Evening)]

Correct Answer: (c) N
Solution:

The difference between the consecutive letters is = (Z - V) = (V - R) = (J - F) = 4
So, the Fourth term/ letter will be
R - 4 = J + 4 = N

47. Select the combination of numbers from the given options, that when sequentially placed in the blanks of the given series will complete the series. [RRB NTPC 19/01/2021 (Morning)]

1, 2, 4 / 2, 3, 36 /__, ____, ____

Correct Answer: (b) 3, 4, 144
Solution:

1² × 2²  = 4
2² × 3² = 36
Similarly, in option (b)
3² × 4² = 144

48. 6, 16, 27, ? [RRB NTPC 19/01/2021 (Morning)]

Correct Answer: (b) 39
Solution:

16 - 6 = 10, 27 - 16 = 11
So next term is 27 + 12 = 39

49. Select the combination of numbers, from the given options, that when sequentially placed in the blanks of the given series will complete the series. [RRB NTPC 19/01/2021 (Morning)]

1, 7, 10, 4, 1, ___, ___

Correct Answer: (d) 7, 10
Solution:

1+ 6 = 7, 7 + 3 = 10 , 10 - 6 = 4 , 4 - 3 = 1
Hence, next absolute difference will also be 6 and 3.
first number = 1 + 6 = 7
Second number = 7 + 3 = 10,

50. Identify the number from the given options, that does NOT belong to the following series. [RRB NTPC 19/01/2021 (Morning)]

1, 7, 25, 61, 125

Correct Answer: (c) 125
Solution: