If a length of the string is 72cm and increases up to 90cm. The increasing percentage will be?

The correct answer is 25%. Percentage increase is calculated by finding the absolute increase (new value minus original value), dividing it by the original value, and then multiplying by 100.

Step-by-Step Solution

• Identify Original and New Lengths:
  
  Original length = 72 cm
  
  New length = 90 cm
• Calculate the Absolute Increase:
  
  Increase = New length - Original length
  
  Increase = 90 - 72 = 18 cm
• Compute the Percentage Increase:
  
  Percentage Increase = (Increase ÷ Original length) × 100
  
  = (18 ÷ 72) × 100
  
  = 0.25 × 100
  
  = 25%
• Verification:
  
  25% of 72 cm = (25/100) × 72 = 18 cm.
  
  72 cm + 18 cm = 90 cm, which matches the new length exactly.

Thus, the increasing percentage is 25%.