Multiple choice

A number is increased by $20$% and then again by $20$%. By what percent should the increased number be reduced so as to get back the original number?

  1. $19\cfrac { 11 }{ 31 } $%
  2. $30\cfrac { 5 }{ 9 } $%
  3. $40$%
  4. $44$%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Original number = 100. After 20% increase: 120. After another 20% increase: 120 * 1.2 = 144. To return to 100, reduction needed = 44. Percent reduction = (44 / 144) * 100 = 4400 / 144 = 30.555...% = 30 5/9%.

AI explanation

Using the successive percentage change formula, an increase of 20% followed by another 20% results in a net increase of 20 + 20 + (20 * 20 / 100) = 44%. Let the original number be 100, making the final number 144. To restore it to 100, we must decrease it by 44, and the required percentage decrease is (44 / 144) * 100 = 275 / 9 = 30 5/9%. The required reduction is 30 5/9%.

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