A towel, when bleached, loses 20% of its length and 10% of its breadth. What is the percentage decrease in its area?

Problem restatementCompute the net percentage change in area when dimensions shrink by given percentages.

Given data

• Length factor = 1 − 0.20 = 0.8
• Breadth factor = 1 − 0.10 = 0.9

Concept/ApproachArea scales as length × breadth, so multiply the scale factors.

Step-by-Step calculation New area factor = 0.8 × 0.9 = 0.72 Percentage decrease = (1 − 0.72) × 100% = 28%

Common pitfalls

• Adding 20% and 10% to get 30% decrease (incorrect; must multiply factors).

Final Answer28%