Question : Directions: By Interchanging the given two numbers which of the following equations will be not correct?
5 and 9
Option 1: 9 × 4 + 5 – 8 ÷ 2 = 25
Option 2: 9 – 5 × 4 + 6 ÷ 3 = –30
Option 3: 9 + 7 × 8 ÷ 4 – 5 = 10
Option 4: 9 – 4 × 5 + 6 ÷ 2 = –28
Correct Answer: 9 – 5 × 4 + 6 ÷ 3 = –30
Solution : Given:
5 and 9
Replace the given symbols in the options one by one with the original symbols in the given equation.
First option: 9 × 4 + 5 – 8 ÷ 2 = 25
⇒ 5 × 4 + 9 – 8 ÷ 2
= 5 × 4 + 9 – 4
= 20 + 9 – 4
= 25
Second option: 9 – 5 × 4 + 6 ÷ 3 = –30
⇒ 5 – 9 × 4 + 6 ÷ 3
= 5 – 9 × 4 + 2
= 5 – 36 + 2
–29 ≠ –30
Third option: 9 + 7 × 8 ÷ 4 – 5 = 10
⇒ 5 + 7 × 8 ÷ 4 – 9
= 5 + 7 × 2 – 9
= 5 + 14 – 9
= 10
Fourth option: 9 – 4 × 5 + 6 ÷ 2 = –28
⇒ 5 – 4 × 9 + 6 ÷ 2
= 5 – 4 × 9 + 3
= 5 – 36 + 3
= –28
Here, only the second option doesn't satisfy the R.H.S. of the given equation. Hence, the second option is correct.
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