1]A rectangle had width 'a' and length 'b'.If the width is decreased by 20% and the length is incresed by 10%.Then what is the area of the new rectangle in percentage compared to ab?
a]12 b]22 c]32 d]42
Let original length be 'b' and 'a'
original area = ab
new length = [(100+10)/100]  * b= (110/100)* b
new breadth = [(100-20)/100] * a = (80/100)*a
new area = (110/100) * b * (80/100)* a = (88/100) *ab
change area = ab - (88/100) * ab = 12 ab/100
% change  or decrease = 12ab/100 * (1/ab) * 100 = 12

2]If the length of a rectangle is increased by 30% while its breadth is decreased by 20%.What is happens to its area?
a]10% decrease b]10% increase c]4% decrease d]4% increase

3]If the length of a rectangle is increased by 70% while its breadth is decreased by 20%.Then percentage decrease in area will be
a]30%  b]32% c]36% d]34%

4]If the length of a rectangle is increased by 10% while its breadth is decreased by 10%.The area of new rectangle is
a]neither increased or decreased b]1% increase c]1% decrease d]none

5]If the length of a rectangle is doubled while its breadth is halved.Then percentage change in area will be
a]50 b]75 c]no change d]none