Aptitude - Area - Discussion
Discussion Forum : Area - General Questions (Q.No. 4)
4.
The percentage increase in the area of a rectangle, if each of its sides is increased by 20% is:
Answer: Option
Explanation:
Let original length = x metres and original breadth = y metres.
Original area = (xy) m2.
| New length = |  |
120 | x |  m |
= | |
6 | x | m. |
| 100 | 5 |
| New breadth = | |
120 | y | m |
= | |
6 | y | m. |
| 100 | 5 |
| New Area = | |
6 | x x | 6 | y | m2 |
= | |
36 | xy | m2. |
| 5 | 5 | 25 |
The difference between the original area = xy and new-area 36/25 xy is
= (36/25)xy - xy
= xy(36/25 - 1)
= xy(11/25) or (11/25)xy
 Increase % = |
|
11 | xy x | 1 | x 100 | % |
= 44%. |
| 25 | xy |
Video Explanation: https://youtu.be/I3jLjLPn1W4
Discussion:
74 comments Page 6 of 8.
Hanny Gupta said:
1 decade ago
A1 = 100*100 = 10000.
A2 = 120*120 = 14400.
A2-A1 = 14400-10000 = 4400.
(A2-A1)% = 44 %.
A2 = 120*120 = 14400.
A2-A1 = 14400-10000 = 4400.
(A2-A1)% = 44 %.
Lork said:
10 years ago
Old a b ==> ab.
New 1.2 a 1.2 b ==> 1.44 ab.
Increase = 1.44 ab - ab = 0.44 = 44%.
New 1.2 a 1.2 b ==> 1.44 ab.
Increase = 1.44 ab - ab = 0.44 = 44%.
Ajit said:
9 years ago
Assume that total area is 100.
20% of 100 = 120.
20% of 120 = 144.
144 - 100 = 44.
20% of 100 = 120.
20% of 120 = 144.
144 - 100 = 44.
Akil said:
3 years ago
It is simple.
(1.2) L* (1.2) B = 1. 44 (L*B).
So, the total area increase is 44%.
(1.2) L* (1.2) B = 1. 44 (L*B).
So, the total area increase is 44%.
(18)
Sdasdasdad said:
1 decade ago
a=l*b=120l*120b.
a=14400lb.
a=100l*100b.
a=10000lb.
%=44/100.
44% answer.
a=14400lb.
a=100l*100b.
a=10000lb.
%=44/100.
44% answer.
Madhu said:
8 years ago
Increases 20% so (120/100) * (120/100) =14400/10000=144%.
44% increases.
44% increases.
MAHESHKRISHNAN D said:
7 years ago
100*100 = 10000(1)
120*120 = 14400(2)
1-2 = 4400/100.
= 44%.
120*120 = 14400(2)
1-2 = 4400/100.
= 44%.
(3)
Subbu said:
5 years ago
Can anyone show how it can be solved by using derivatives? please.
(1)
Hema said:
1 decade ago
Why here you take length = (120/100)x and breadth = (120/100)y?
Harmanpreet said:
7 years ago
Each side 20% increased thus 120*120/100=144,
then 144-100 =44.
then 144-100 =44.
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