Missing Number – Railway Reasoning part – 1

Total Questions: 50

21. Find the missing number to complete the following sequence: [NTPC CBT - I 11/02/2021 (Evening)]

Correct Answer: (d) 13
Solution:

3² + 2² = 7 + 6
2² + 6² = 25 + 15
2² + 5² = 20 + 9
3² + 4² = 12 + 13

22. Find the missing number to complete the following sequence: [NTPC CBT - I 15/02/2021 (Morning)]

Correct Answer: (d) 8
Solution:

23. If 31 C 19 D 57 = 93 and 52 C 13 D 5 = 20, then 98 C 14 D 11 = ? [NTPC CBT - I 15/02/2021 (Evening)]

Correct Answer: (b) 77
Solution:

24. Find the missing number to complete the following sequence: [NTPC CBT - I 17/02/2021 (Morning)]

Correct Answer: (d) 4
Solution:

5 + 4 + 7 + 8 = 24 = 6 × 4
6 + 10 + 8 + 18 = 42 = 7 × 6
Similarly,
12 + 8 + 3 + 9 = 32 = 4 × 8
? = 4

25. Find the missing number to complete the following sequence: [NTPC CBT - I 17/02/2021 (Morning)]

Correct Answer: (a) 7
Solution:

6 × 5 = 2² + 1² + 5² = 30
5 × 10 = 3² + 5² + 4² = 50
7 × 2 = 1² + 3² + 2² = 14

26. 199 = 18, 267 = 19, 456 = 26, then 678 = ? [NTPC CBT - I 02/03/2021 (Evening)]

Correct Answer: (b) 50
Solution:

1 × 9 + 9 = 18
2 × 6 + 7 = 19
4 × 5 + 6 = 26
6 × 7 + 8 = 50

27. Find the missing number to complete the following sequence: [NTPC CBT - I 03/03/2021 (Morning)]

Correct Answer: (b) R
Solution:

F + 5 = K, K + 3 = N, N + 7 = U, U + 5 = Z, Z + 3 = C, C + 7 = J, J + 5 = O, O + 3 = R

28. The rectangle represents a set of calculations that are common across all the given equations. Identify the calculations involved and solve the fourth equation on the same basis. [NTPC CBT - I 08/03/2021 (Morning)]

Correct Answer: (d)
Solution:

Here for the first term 7 ▃ 3 =

For the second term 6 ▃ 2 =

For the third term 5 ▃ 3 =

So, for the fourth term a ▃ b =

29. Find the missing number to complete the following sequence: [NTPC CBT - I 11/03/2021 (Evening)]

Correct Answer: (d) 5
Solution:

In 1st fig. ( 4 - 3 ) = 1 and (7 - 5) = 2 now , (1 + 2 )³ = 27
In 2nd fig. ( 6 - 2 ) = 4 and (5 - 3) = 2 now, (4 + 2 )³ = 216
In 3rd fig. ( 4 - 1 ) = 3 and ( 9 - 5 ) = 4 now, ( 3 + 4 )³ = 343

30. Study the given figure carefully and select the number that can replace the ‘X’. [NTPC CBT - I 13/03/2021 (Evening)]

Correct Answer: (c) 17
Solution:

1st row + 3rd row = 2nd row
And 3rd row + 5th row = 4th row
Example - 11 + 6 = x ⇒ 17