Mathematical Operations – Railway Reasoning (part – 5)

Total Questions: 26

11. In the following question, correct the equation by interchanging the two signs. [RRB JE 25/05/2019 (Afternoon)]

4 × 3 − 6 ÷ 2 + 7 = 8

Correct Answer: (c) + and -
Solution:

Given,
4 × 3 - 6 ÷ 2 + 7 = 8
By checking all the options one by one we found that only option (c) satisfies so
as per that,
4 × 3 + 6 ÷ 2 - 7 ⇒ 12 + 3 - 7 = 8 (RHS)

12. In the following question, correct the equation by interchanging the two signs. [RRB JE 28/05/2019 (Afternoon)]

5 + 6 ÷ 3 - 2 × 5 = 13

Correct Answer: (a) + and ×
Solution:

Given,5 + 6 ÷ 3 - 2 × 5 = 13
By checking all the options one by one we found that only option (a) satisfies so
as per that,
5 × 6 ÷ 3 - 2 + 5 = 10 + 3 = 13 (RHS)

13. If '×' means '÷', '-' means '×', '÷' means '+', and '+' means '-', then 3 - 15 ÷ 16 × 8 + 6 = ? [RRB JE 30/05/2019 (Afternoon)]

Correct Answer: (d) 41
Solution:

Given, 3 - 15 ÷ 16 × 8 + 6
By applying conditions as per question we get,
3 × 15 + 16 ÷ 8 - 6 = 45 + 2 - 6 = 41

14. In the following question, which one of the four interchanges in signs and numbers would make the given equation correct? [RRB JE 31/05/2019 (Afternoon)]

15 + 4 - 2 × 7 = 27

Correct Answer: (b) × and ÷; 4 and 15
Solution:

Given, 15 + 4 - 2 × 7 = 27
By checking all the options one by one we found that only option (b) satisfies so
as per that,
4 + 15 × 2 - 7 ⇒ 4 + 30 - 7 = 27 (RHS)

15. If '+' means '-', '-' means '×', '×' means '÷', and '÷' means '+', then 15 × 3 ÷ 15 + 5 - 2 = ? [RRB JE 01/06/2019 (Morning)]

Correct Answer: (b) 10
Solution:

Given, 15 × 3 ÷ 15 + 5 - 2
By applying condition as per question we get,
15 ÷ 3 + 15 - 5 × 2 ⇒ 5 + 15 - 10 = 10

16. In a code language, '+' represents '×', '-' represents '+', '×' represents '÷' and '÷' represents '-'. Find the answer to the following mathematical expression in the same code language: [ALP Tier II 21/01/2019 (Morning)]

2 - 6 × 3 + 4 = ?

Correct Answer: (b) 10
Solution:

Given expression :
2 - 6 × 3 + 4
After interchanging the symbols,
2 + 6 ÷ 3 × 4 = 2 + 2 × 4 = 2 + 8 = 10

17. Which two signs should be interchanged to make the following equation mathematically correct? [ALP Tier II 21/01/2019 (Morning)]

12 - 3 + 8 × 2 ÷ 4 = 16

 

Correct Answer: (b) ÷ and -
Solution:

Given expression :
12 - 3 + 8 × 2 ÷ 4 = 16
Check each option one by one and satisfies the expression. We get option
(b) satisfies the equation.
12 ÷ 3 + 8 × 2 - 4 = 16
⇒ 4 + 16 - 4 = 16 ⇒ 16 = 16

18. In a certain code language, '+' represents '×', '-' represents '+', '÷' represents '÷' and '×' represents '-'. Then substitutes the value of the following expression on the base. [ALP Tier II 21/01/2019 (Afternoon)]

9 × 3 - 4 + 10 - 8 = ?

Correct Answer: (c) 11
Solution:

Given expression :
9 × 3 ÷ 4 + 10 - 8
After interchanging the signs,
9 - 3 + 4 × 10 ÷ 8 = 9 - 3 + 4 × 10/8
= 9 - 3 + 5 = 14 - 3 = 11

19. Which two signs should be interchanged to make the given equation correct ? [ALP Tier II 21/01/2019 (Evening)]

15 ÷ 3 + 2 × 10 - 6 = 14

Correct Answer: (a) + and ×
Solution:

Given expression :
15 ÷ 3 + 2 × 10 - 6 = 14
Check each option one by one we get option (a) satisfies the equation.
⇒ 15 ÷ 3 × 2 + 10 - 6 = 14
⇒ 5 × 2 + 10 - 6 = 14 ⇒ 10 + 10 - 6 = 14
⇒ 20 - 6 = 14 ⇒ 14 = 14
L.H.S = R.H.S

20. In a certain code language, '+' represents '×', '-' represents '+', '×' represents '÷' and '÷' represents '-', calculate the answer to the following equation. [ALP Tier II 21/01/2019 (Evening)]

8 + 3 × 4 - 2 = ?

Correct Answer: (b) 8
Solution:

Given expression :
8 + 3 × 4 - 2
As per the instructions,
8 × 3 ÷ 4 + 2 = 8 × 3/4 + 2 = 6 + 2 = 8