Which of the following interchange of numbers and signs would make the given equation correct?
512 × 64 ÷ 5 + 30 - 50 = 20
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 20 and 50, × and ÷.
Given equation: 512 × 64 ÷ 5 + 30 - 50 = 20
Now, interchanging the two numbers and two signs in the givren options one by one:
Option (1) 50 and 64, + and ×
512 + 50 ÷ 5 × 30 - 64 = 20
⇒ 512 + 50 ÷ 5 × 30 - 64 = 20
⇒ 512 + 10 × 30 - 64 = 20
⇒ 512 + 300 - 64 = 20
⇒ 812 - 64 = 20
⇒ 748 ≠ 20
Option (2) 20 and 30, + and ÷
⇒ 512 × 64 + 5 ÷ 20 - 50 = 30
⇒ 512 × 64 + 0.25 - 50 = 30
⇒ 32768 + 0.25 - 50 = 30
⇒ 32768.25 - 50 = 30
⇒ 32718.25 ≠ 30
Option (3) 20 and 50, × and ÷
⇒ 512 ÷ 64 c 5 + 30 - 20 = 50
⇒ 8 × 5 + 30 - 20 = 50
⇒ 40 + 30 - 20 = 50
⇒ 70 - 20 = 50
⇒ 50 = 50
Thus, by interchanging 20 and 50, × and ÷ makes the equation correct so their is no need to solve the option 4.
Hence, 20 and 50, × and ÷ is the correct answer.