Mathematical Operations – Railway Reasoning (part – 3)

Total Questions: 50

21. Which two signs should be interchanged to make the following equation correct ? [Level 6 (09/05/2022) Shift 2]

12 − 4 + 8 × 3 ÷ 7 = 20

Correct Answer: (c) ÷, −
Solution:

On going by options one by one, we get with option (c)
12 – 4 + 8 × 3 ÷ 7 = 20 becomes
12 ÷ 4 + 8 × 3 – 7 ⇒ 3 + 24 - 7 = 20
Hence satisfied.

22. From the given options, which two numbers should be interchanged so that the value of Y becomes 29? [Level 5 (12/06/2022) Shift 1]

6 × 4 − 5 + 9 ÷ 3 = Y

Correct Answer: (b) 4 and 5
Solution:

6 × 4 - 5 + 9 ÷ 3 = Y
the value of Y = 29
By hit and trial method, go through option (b),
6 × 4 - 5 + 9 ÷ 3 = 29
As per the instruction,
6 × 5 - 4 + 9 ÷ 3 = 29
⇒ 30 - 4 + 3 = 29 ⇒ 29 = 29 (Satisfy)

23. Which two signs and numbers need to be interchanged to make the following equation correct? [Level 2 (13/06/2022) Shift 1]

2 + 8 ÷ 5 × 4 − 6 = 3

Correct Answer: (a) ÷, × and 2,5
Solution:

2 + 8 ÷ 5 × 4 - 6 = 3
By hit and trial method, Go through option (a)
5 + 8 × 2 ÷ 4 - 6 = 3
5 + 4 - 6 = 3 ⇒ 3 = 3 (satisfy)

24. If Q means ‘+’, J means ‘×’, T means ‘−’, and K means ‘÷’, then 52 K 4 Q 6 J 12 T 8 = ? [Level 2 (13/06/2022) Shift 2]

Correct Answer: (d) 77
Solution:

52 K 4 Q 6 J 12 T 8
As per question,
⇒ 52 ÷ 4 + 6 × 12 - 8 ⇒ 13 + 72 - 8 = 77

25. Which two signs and which two numbers should be interchanged to make the following equation correct? [Level 2 (13/06/2022) Shift 2]

630 ÷ 6 - 5 ÷ 40 × 10 = 295

Correct Answer: (a) ÷, + and 5, 10
Solution:

630 ÷ 6 - 5 ÷ 40 × 10 = 295
By hit and trial method, Go through option (a)
630 ÷ 6 - 10 + 40 × 5 = 295
⇒ 105 - 10 + 200 = 295
⇒ 295 = 295 (Satisfy)

26. If ‘÷’ is replaced with ‘+’, ‘×’ is replaced with ‘÷’, ‘+’ is replaced with ‘×’ and ‘−’ is replaced with ÷, then what will be the value of the given expression? [Level 3 (14/06/2022) Shift 1]

8 + 5 × 54 − 9 ÷ 3 ?

Correct Answer: (b) 37
Solution:

8 + 5 × 54 – 9 ÷ 3 ?
As per question,
8 × 5 - 54 ÷ 9 + 3 ⇒ 40 - 6 + 3 = 37

27. If ‘×’ stands for subtraction, ÷ stands for addition, + stands for division, and − stands for multiplication, which of the following equation is correct? [Level 5 (15/06/2022) Shift 3]

Correct Answer: (d) 16 ÷ 20 − 6 + 10 × 2 = 16
Solution:

16 ÷ 20 – 6 + 10 × 12 = 16
Substituting the symbols in option (d) as instructed in the question, option (d) is satisfied.
⇒ 16 + 20 × 6 ÷ 10 – 12
⇒ 16 + 12 – 12 ⇒ 16 = RHS (Satisfied)

28. Which two signs should be interchanged to make the following equation correct? [Level 2 (16/06/2022) Shift 1]

24 × 36 ÷ 27 + 6 – 2 = 22

Correct Answer: (d) ÷ and ×
Solution:

24 × 36 ÷ 27 + 6 – 2 = 22
Interchanging the symbols given in option (d) in the above expression, it is satisfied.
= 24 ÷ 36 × 27 + 6 – 2
= 18 + 6 – 2 = 22 = RHS (Satisfied)

29. Select the correct combination of mathematical signs that can sequentially replace the * signs and balance the given equation. [Level 2 (16/06/2022) Shift 2]

25 * 15 * 5 * 4 * 16 * 21

Correct Answer: (d) +, ÷, ×, -, =
Solution:

25 ✱ 15 ✱ 5 ✱ 4 ✱ 16 ✱ 21
In the above expression, by sequentially substituting all the symbols given in option (d), satisfies ,
25 + 15 ÷ 5 × 4 – 16 = 21
25 + 12 – 16 = 21
⇒ 37 – 16 = 21 ⇒ 21 = 21 (Satisfied)

30. Select the correct combination of mathematical signs that can sequentially replace the * signs and balance the given equation. [Level 2 (16/06/2022) Shift 3]

19 * 5 * 4 * 2 * 4 * 13

Correct Answer: (c) −, ×, ÷, +, =
Solution:

19 ✱ 5 ✱ 4 ✱ 2 ✱ 4 ✱ 13
Substituting all the symbols given in option (c) at the place of (✱) given in the question,
19 − 5 × 4 ÷ 2 + 4 = 13
19 − 10 + 4 = 13
13 = 13 (Satisfied)