$20 \div 5 + 6 \times 2 - 4 = 18$
$\div$ and $-$
The problem asks us to identify which two mathematical signs need to be swapped in the equation '$20 \div 5 + 6 \times 2 - 4 = 18$' to make it correct. We need to test the given options.
Evaluating the Original Equation
First, let's calculate the value of the original equation using the standard order of operations (PEMDAS/BODMAS): Division, Multiplication, Addition, Subtraction.
- Division: $20 \div 5 = 4$
- Multiplication: $6 \times 2 = 12$
- The equation becomes: $4 + 12 - 4$
- Addition: $4 + 12 = 16$
- Subtraction: $16 - 4 = 12$
The original equation evaluates to $12$, not $18$. Therefore, a swap is needed.
Testing Sign Swaps
We will test each option by swapping the specified signs and re-evaluating the equation.
Option 1: Swap $\div$ and $\times$
The equation becomes: $20 \times 5 + 6 \div 2 - 4$
- Multiplication: $20 \times 5 = 100$
- Division: $6 \div 2 = 3$
- The equation becomes: $100 + 3 - 4$
- Result: $103 - 4 = 99$. (Incorrect)
Option 2: Swap $+$ and $-$
The equation becomes: $20 \div 5 - 6 \times 2 + 4$
- Division: $20 \div 5 = 4$
- Multiplication: $6 \times 2 = 12$
- The equation becomes: $4 - 12 + 4$
- Result: $-8 + 4 = -4$. (Incorrect)
Option 3: Swap $\div$ and $-$
The equation becomes: $20 - 5 + 6 \times 2 \div 4$
- Multiplication: $6 \times 2 = 12$
- Division: $12 \div 4 = 3$
- The equation becomes: $20 - 5 + 3$
- Subtraction: $20 - 5 = 15$
- Addition: $15 + 3 = 18$
This results in $18$, which matches the right side of the equation. This is the correct swap.
Option 4: Swap $+$ and $\times$
The equation becomes: $20 \div 5 \times 6 + 2 - 4$
- Division: $20 \div 5 = 4$
- Multiplication: $4 \times 6 = 24$
- The equation becomes: $24 + 2 - 4$
- Result: $26 - 4 = 22$. (Incorrect)
Conclusion
Swapping the division ($\div$) sign and the minus ($-$) sign corrects the equation. The correct option involves swapping $\div$ and $-$.
Similar Questions
- Which two signs should be interchanged to make the following equation CORRECT?
$[(15 \div 3) - (4 \times 2)] + [4 - 6] = 5 \times 10$ - If "+" means "$\div$", "-" means "+", "$\times$" means "-" and "$\div$" means "$\times$", which of the following options is CORRECT?
- If 5 @ 2 = 17 and 6 @ 3 = 27, what is 7 @ 4?
- If 9 @ 1 = 82 and 6 @ 2 = 38, what is the value of 7 @ 3?
- You are given a mathematical expression with basic operations. However, the symbols used are not their usual meaning.
You must follow these symbol substitution rules:
'+' means '-'
'-' means 'x'
'x' means '÷'
'÷' means '+'
$120 \div 6 \times 3 - 10 + 4 = ?$ - If $\times$ stands for addition, $\div$ stands for subtraction, + stands for multiplication, and - stands for division, then $12 \times 6 \div 3 - 2 + 5 = ?$
- Which two signs need to be interchanged?
$22 - 4 \times 2 \div 2 + 6 = 20$ - Which interchanges of numbers and signs will make the equation correct? $8 \times 3 + 4 = 28$
- Select the CORRECT sequence of mathematical signs to sequentially replace the A and B to balance the given equation.
15 A 5 B 4 = 35 - The following equation is incorrect. Which two signs should be interchanged to correct the equation?
$14 - 7 \times 30 \div 10 + 4 = 54$
Important Questions from Mathematical Operations
What will come in the place of ‘?’ in the following equation if ‘+’ and ‘−’ are interchanged and ‘×’ and ‘÷’ are interchanged?
18 ÷ 9 + 24 × 3 − 16 = ?If ‘A’ stands for ‘÷’, ‘B’ stands for ‘×’, ‘C’ stands for ‘+’, and ‘D’ stands for ‘−’, what will come in place of the question mark (?) in the following equation?
88 B 3 D 12 A 4 C 6 = ?Select the set in which the numbers are related in the same way as are the numbers of the given sets.
(NOTE: Operations should be performed on whole numbers without breaking down the numbers into their constituent digits. E.g., 13 – Operations on 13 such as adding/subtracting/multiplying, etc., to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.)
Given sets:
(9, 21, 193)
(12, 15, 184)What will come in the place of the question mark (?) in the following equation, if ‘÷’ and ‘+’ are interchanged and ‘−’ and ‘×’ are interchanged?
44 ÷ 78 + 6 − 3 × 19 = ?Two sets of numbers are given below. In each set of numbers, certain mathematical operation(s) on the first number result(s) in the second number. Similarly, certain mathematical operation(s) on the second number result(s) in the third number and so on. Which of the given options follows the same set of operations as in the given sets?
(NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into their constituent digits. E.g. 13 – Operations on 13 such as adding/subtracting/multiplying to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.)
