Mathematical Operations – Railway Reasoning (part – 3)

Total Questions: 50

31. If ‘ + ‘ means division, ‘ ÷ ‘ means subtraction, ‘ - ‘ means multiplication, and ‘ × ‘ means addition, then what is the value of the given expression? [Level 3 (17/06/2022) Shift 1]

175 - 10 + 2 × 165 ÷ 25 + 5 = ?

Correct Answer: (c) 1035
Solution:

175 − 10 + 2 × 165 ÷ 25 + 5
On interchanging the symbols as given in the question,
175 × 10 ÷ 2 + 165 − 25 ÷ 5
⇒ 875 + 165 − 5 ⇒ 1040 − 5 = 1035

32. If ÷ means addition, × means subtraction, + means multiplication and - means division then [Level 3 (17/06/2022) Shift 3]

40 - 20 + 6 × 2 ÷ 5 = ?

Correct Answer: (d) 15
Solution:

40 − 20 + 6 × 2 ÷ 5
On substituting the given symbols according to the question, we get
40 ÷ 20 × 6 − 2 + 5
⇒ 2 × 6 − 2 + 5 = 12 − 2 + 5 = 15

33. If A means ‘+’, S means ‘-’, M means ‘×’, D means ‘÷’, B means ‘(’ and F means ‘)’, then solve the following expression : [RRB NTPC 28/12/2020 (Evening)]

B700A110S90FDB9M10S10F

Correct Answer: (a) 9
Solution:After putting all the signs, the
expression becomes,
⇒ B700A110S90FDB9M10S10F
= (700 + 110 − 90) ÷ (9 × 10 − 10)
= 720/80 = 9

34. f ‘@’ indicates either ‘+’ or ‘×’, what will be the minimum value of ‘1 @ 2 @ 3 @ 4 @ 5’? [RRB NTPC 29/12/2020 (Morning)]

(Note: we have choice to replace each of the four @ signs in the expression by either ‘+’ or ‘×’ operation)

Correct Answer: (a) 14
Solution:

As we know (1 × 2) < (1 + 2)
and this is the only case where sum is greater than multiplication.
So, in the first case, we will take @ = ×
and in all other cases we will take @ = +
The minimum value of the given
expression.
⇒ 1 @ 2 @ 3 @ 4 @ 5
= 1 × 2 + 3 + 4 + 5 = 14

35. If + means -, - means ÷, × means + and ÷ means ×, then what will be the value of the expression 13 + 6 ÷ 2 × 32 - 2 ? [RRB NTPC 29/12/2020 (Evening)]

Correct Answer: (b) 17
Solution:

After putting the interchanged signs,
= 13 − 6 × 2 + 32 ÷ 2 = 13 − 12 + 16 = 17

36. If + is replaced by -, × is replaced by + and - by × then 28 + (5 × 7) - 9 6 will be equal to [RRB NTPC 30/12/2020 (Morning)]

Correct Answer: (d) 10
Solution:

37. If ‘+’ = ‘÷’, ‘×’ = ‘+’, ‘-’ = ‘×’ and ‘÷’ = ‘-’ then which of the following equations is correct? [RRB NTPC 30/12/2020 (Evening)]

Correct Answer: (a) 36 – 6 + 3 × 5 ÷ 3 = 74
Solution:

As, + = ÷, × = +, − = ×
and ÷ = −,
Then, from the below expressions, we get option (a)
LHS = 36 − 6 + 3 × 5 ÷ 3
= 36 × 6 ÷ 3 + 5 − 3 = 74 = RHS.

38. If + denotes ‘multiplication’, − denotes ‘addition’, × denotes ‘division’ and ÷ denotes ‘subtraction’, then which of the following equations is true? [RRB NTPC 04/01/2021 (Morning)]

Correct Answer: (b) 10 – 12 ÷ 18 × 6 + 2 = 16
Solution:

After changing the signs in option (b),
10 + 12 − 18 ÷ 6 × 2 = 16
⇒ 22 − 6 = 16 ⇒ 16 = 16

39. If A represents ‘subtraction’, B represents ‘multiplication’, C represents ‘division’, and D represents ‘addition’, then what is the value of (3 B 4 D 5 A 6) C 1? [RRB NTPC 04/01/2021 (Evening)]

Correct Answer: (c) 11
Solution:

(3 B 4 D 5 A 6) C 1
After putting all the correct signs,
= (3 × 4 + 5 − 6) ÷ 1 = 11 ÷ 1 = 11.

40. If × stands for addition, ÷ stands for subtraction, + stands for multiplication and - stands for division, then 10 × 4 ÷ 4 - 2 + 1 = ? [RRB NTPC 05/01/2021 (Morning)]

Correct Answer: (d) 12
Solution:

Given: 10 × 4 ÷ 4 − 2 + 1
After putting the correct signs,
= 10 + 4 − 4 ÷ 2 × 1 = 14 − 2 = 12