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 4 of 8.
Sourav said:
1 decade ago
Easiest approach:
Length 10 cm.
Breadth 10 cm.
Area = 10*10 = 100 cm.
With 20% increase:
Length 12 cm.
Breadth 12 cm.
Area 144 cm.
Percentage increase (144-100) = 44.
Ans: 44%.
Length 10 cm.
Breadth 10 cm.
Area = 10*10 = 100 cm.
With 20% increase:
Length 12 cm.
Breadth 12 cm.
Area 144 cm.
Percentage increase (144-100) = 44.
Ans: 44%.
Gnit said:
1 decade ago
Let the area be 100.
Since length and area are proportional 20% increase in length => area = 120 since breadth and area are proportional 20 % increase in breadth => area = 144. Therefore, 144-100 = 44.
Since length and area are proportional 20% increase in length => area = 120 since breadth and area are proportional 20 % increase in breadth => area = 144. Therefore, 144-100 = 44.
SUKUMAR SATYEN said:
1 decade ago
Let's assume Length = L cm and Breadth = B cm.
=> Area (old) = L*B = LB....equation (1).
When, Length is increased by 20%, Length = 1.2L.
When, Breadth is increased by 20%, Breadth = 1.2B.
=> Area (increased) = 1.2L*1.2B = 1.44LB.....equation (2).
Using equation (1) and (2).
=> LB (1+% increase/100) = 1.44LB.
=> % increase = (1.44-1)*100 = 0.44*100 = 44 per cent.
=> Area (old) = L*B = LB....equation (1).
When, Length is increased by 20%, Length = 1.2L.
When, Breadth is increased by 20%, Breadth = 1.2B.
=> Area (increased) = 1.2L*1.2B = 1.44LB.....equation (2).
Using equation (1) and (2).
=> LB (1+% increase/100) = 1.44LB.
=> % increase = (1.44-1)*100 = 0.44*100 = 44 per cent.
Priyanka said:
10 years ago
Let the length be 100 and breadth be 200.
So area = l*b = 20000.
If both the sides increases by 20% then,
The new length = 120 and new breadth = 240.
New area = 120*240 = 28800.
So % increase in area = (28800-20000)/20000*100 which is coming out to be 44%.
So area = l*b = 20000.
If both the sides increases by 20% then,
The new length = 120 and new breadth = 240.
New area = 120*240 = 28800.
So % increase in area = (28800-20000)/20000*100 which is coming out to be 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%.
Kumar said:
10 years ago
I can't understand your answer. Please explain brief.
NAVEEN said:
9 years ago
Given sides of rectangle are increased by 20%.
Let us take length L = 20.
Breadth B = 10.
Area of rectangle = LxB = 10x20 = 200.
After 20% increase L = 24.
B = 12.
Area of rectangle = LxB = 24x12 = 288.
Area increased to 288 from 200 = 44%.
Same for square.
Let us take length L = 20.
Breadth B = 10.
Area of rectangle = LxB = 10x20 = 200.
After 20% increase L = 24.
B = 12.
Area of rectangle = LxB = 24x12 = 288.
Area increased to 288 from 200 = 44%.
Same for square.
Shailesh said:
9 years ago
Make it simple yar! Parentage increase increase of rectangle or square will be same.
Assume 10 x 10 original square Area will be 100 simple.
Now increase side length by 20 % will make 12 x 12 square Area will be 144.
So simple should I tell you the correct answer (C) 44.
Assume 10 x 10 original square Area will be 100 simple.
Now increase side length by 20 % will make 12 x 12 square Area will be 144.
So simple should I tell you the correct answer (C) 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.
Ramesh said:
9 years ago
Let original length and breadth be 100.
So new length and breadth are 120
New Area = 120 * 120 so 14400.
Old area = 100 * 100 = 10000.
So diff = 4400.
Error = 4400/(100 * 100) * 100.
So, 44%.
So new length and breadth are 120
New Area = 120 * 120 so 14400.
Old area = 100 * 100 = 10000.
So diff = 4400.
Error = 4400/(100 * 100) * 100.
So, 44%.
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