Question : Directions: By interchanging the given two signs and numbers which of the following equations will be correct?
+ and –, 7 and 6
Option 1: 4 × 7 + 6 – 3 ÷ 1 = 20
Option 2: 8 × 7 + 5 ÷ 1 – 6 = 17
Option 3: 7 – 6 × 3 + 4 ÷ 1 = 8
Option 4: 7 × 2 – 6 + 4 ÷ 2 = 13
Correct Answer: 4 × 7 + 6 – 3 ÷ 1 = 20
Solution :
Let's check the options –
First option:
4 × 7 + 6 – 3 ÷ 1 = 20
On interchanging the given numbers and signs, the equation becomes –
⇒ 4 × 6 – 7 + 3 ÷ 1 = 20
Solving the L.H.S. of the equation –
= 4 × 6 – 7 + 3
= 24 – 7 + 3
= 20
Second option:
8 × 7 + 5 ÷ 1 – 6 = 17
On interchanging the given numbers and signs, the equation becomes –
⇒ 8 × 6 – 5 ÷ 1 + 7 = 17
Solving the L.H.S. of the equation –
= 8 × 6 – 5 + 7
= 48 – 5 + 7
= 50 ≠ 17
Third option:
7 – 6 × 3 + 4 ÷ 1 = 8
On interchanging the given numbers and signs, the equation becomes –
⇒ 6 + 7 × 3 – 4 ÷ 1 = 8
Solving the L.H.S. of the equation –
= 6 + 7 × 3 – 4
= 6 + 21 – 4
= 23 ≠ 8
Fourth option:
7 × 2 – 6 + 4 ÷ 2 = 13
On interchanging the given numbers and signs, the equation becomes –
⇒ 6 × 2 + 7 – 4 ÷ 2 = 13
Solving the L.H.S. of the equation –
= 6 × 2 + 7 – 2
= 12 + 7 – 2
= 17 ≠ 13
So, only the equation in the first option satisfies the R.H.S. of the given equation. Hence the first option is correct.
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