Question : Directions: Which two numbers should be interchanged to make the given equation correct?
5 – 4 ÷ 2 × 10 + 7 = 7
Option 1: 10 and 2
Option 2: 5 and 7
Option 3: 5 and 2
Option 4: 10 and 5
Correct Answer: 10 and 5
Solution :
Given:
5 – 4 ÷ 2 × 10 + 7 = 7
Let's check each option –
First option:
10 and 2
On interchanging the numbers, we get –
5 – 4 ÷ 10 × 2 + 7 = 7
On solving the L.H.S. of the equation –
= 5 – 4 ÷ 10 × 2 + 7
= 5 – 0.4 × 2 + 7
= 5 – 0.8 + 7
= 11.2 ≠ 7
Second option:
5 and 7
On interchanging the numbers, we get –
7 – 4 ÷ 2 × 10 + 5 = 5
On solving the L.H.S. of the equation –
= 7 – 4 ÷ 2 × 10 + 5
= 7 – 2 × 10 + 5
= 7 – 20 + 5
= –8 ≠ 5
Third option:
5 and 2
On interchanging the numbers, we get –
2 – 4 ÷ 5 × 10 + 7 = 7
On solving the L.H.S. of the equation –
= 2 – 4 ÷ 5 × 10 + 7
= 2 – 0.8 × 10 + 7
= 2 – 8 + 7
= 1 ≠ 7
Fourth option:
10 and 5
On interchanging the numbers, we get –
10 – 4 ÷ 2 × 5 + 7 = 7
On solving the L.H.S. of the equation –
= 10 – 4 ÷ 2 × 5 + 7
= 10 – 2 × 5 + 7
= 10 – 10 + 7
= 7
So, only the fourth option satisfies the equation. Hence, the fourth option is correct.
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