By interchanging the given two signs and numbers which of the following equation will be not correct?
× and ÷, 2 and 6
I. 7 – 4 × 3 ÷ 6 + 2 = 8
II. 6 – 8 × 2 + 9 ÷ 3 = 5
Both I and II
This problem requires us to evaluate two equations after applying specific rules for interchanging signs and numbers. We need to swap the multiplication sign (×) with the division sign (÷) and the number 2 with the number 6 in both equations. After performing the interchanges, we will check if the resulting equations are correct based on standard mathematical operations.
The original Equation I is:
\(7 - 4 \times 3 \div 6 + 2 = 8\)
Now, let's apply the given interchanges to Equation I:
Applying these rules, the new equation becomes:
\(7 - 4 \div 3 \times 2 + 6\)
Let's evaluate this expression using the order of operations (BODMAS/PEMDAS):
The calculated value of the left side is \(\frac{31}{3}\). The original equation stated the result is 8. Since \(\frac{31}{3} \neq 8\) (because \(8 = \frac{24}{3}\)), Equation I is NOT correct after the interchange.
The original Equation II is:
\(6 - 8 \times 2 + 9 \div 3 = 5\)
Now, let's apply the given interchanges to Equation II:
Applying these rules, the new equation becomes:
\(2 - 8 \div 6 + 9 \times 3\)
Let's evaluate this expression using the order of operations (BODMAS/PEMDAS):
The calculated value of the left side is \(\frac{83}{3}\). The original equation stated the result is 5. Since \(\frac{83}{3} \neq 5\) (because \(5 = \frac{15}{3}\)), Equation II is NOT correct after the interchange.
After interchanging the signs (× and ÷) and the numbers (2 and 6):
Therefore, both Equation I and Equation II will be not correct after the specified interchanges.
| Equation | Original | After Interchange | Calculated Value (Interchanged) | Original Expected Value | Correct/Not Correct (After Interchange) |
|---|---|---|---|---|---|
| I | \(7 - 4 \times 3 \div 6 + 2 = 8\) | \(7 - 4 \div 3 \times 2 + 6\) | \(\frac{31}{3}\) | 8 | Not Correct |
| II | \(6 - 8 \times 2 + 9 \div 3 = 5\) | \(2 - 8 \div 6 + 9 \times 3\) | \(\frac{83}{3}\) | 5 | Not Correct |
| Operation/Number | Original | Interchanged With |
|---|---|---|
| Sign 1 | × | ÷ |
| Sign 2 | ÷ | × |
| Number 1 | 2 | 6 |
| Number 2 | 6 | 2 |
When evaluating mathematical expressions, we follow a specific order of operations to ensure consistency in results. This order is often remembered using acronyms like BODMAS or PEMDAS.
In this problem, we used Division and Multiplication before Addition and Subtraction, working from left to right for operations at the same level.
Which two numbers should be interchanged to make the given equation correct?
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23 + 84 ÷ 14 × 8 − 3 = 5
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