Question

When the sides of a square is decreased by 10% , then its area is decreased by :

• A. 18%
• B. 19%
• C. 20%
• D. 21%

Answer 1

Answer:

B. 19%

ORIGINAL AREA = a² length of side when 10% decreased a - a x 10/100 = a - a/10 =9a/10 New area = (9a/10)² = 8s²/100 decrease area = a²- 81a²/100 =100a²-81a²/100 =19a²/100 %= 19a²/100/a² x 100 =19a²/100a² x 100 = 19%