the length and breadth of a square are increased by 40 30..., Area, General Mathematics

Question:The length and breadth of a square are increased by 40% and 30% respectively. The area of the resulting rectangle exceeds the area of the square by :

A `35%` 
B `42%` 
C `62%` 
D `82%`

/98

+ AnswerD

+ ExplanationLet side of the square be a. Then, area` = a^2`.

New length` = ((140)/(100) a)`

                 `= (7a)/5,`

New breadth` = ((130)/(100) a)`

                   `= (13a)/10.`

New area` = (7a)/5 xx (13a)/10`

             `= (91a^2)/50`

Increase in area` = (41/50 a^2 xx 1/a^2 xx 100)%`

                           `= 82%`

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