Question:The length of a rectangle is increased by `20%` and the width is decreased by `20%`. The area decreases by :
A `0.8%`
B `1.2%`
C `4%`
D `8%`
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+ Answer
C
+ Explanation`Let∕`= 10 m & b = 10 m.
Then, area`= 100 m^2`
New length`= 120% of 10 = 12 m.`
New breadth`= 80% of 10 = 8 m`.
New area`= (12 xx 8) m^2`
`= 96 m^2`
Decrease`= 4%`.