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.
Ravali yadav said:
8 years ago
Assume it as 100.
increase 20 for 100 then it will become 120,
again increase 20% for 120, then it will become 144,
100----------20%-----120-------20%(24)------120+24 = 144.
increase 20 for 100 then it will become 120,
again increase 20% for 120, then it will become 144,
100----------20%-----120-------20%(24)------120+24 = 144.
Krishna said:
1 decade ago
Old area:
length=l
breadth=b
area=lb
new area:
length=(120/100)l = 6l/5
breadth=(120/100)b=6b/5
area=36lb/25
error% = (n.a - o.a)*100/o.a
=(((36lb/25)-lb)*100)/lb
=44%
length=l
breadth=b
area=lb
new area:
length=(120/100)l = 6l/5
breadth=(120/100)b=6b/5
area=36lb/25
error% = (n.a - o.a)*100/o.a
=(((36lb/25)-lb)*100)/lb
=44%
Sivasankari said:
1 decade ago
Just we take before increment area is 100%l * 100%b = lb
After 20% of increment area is 120%l * 120%b=1.44lb from this we get 0.44 that is 44% was increased....
After 20% of increment area is 120%l * 120%b=1.44lb from this we get 0.44 that is 44% was increased....
ER RAJKUMAR ARYA said:
8 years ago
Let, l = b = 1 unit.
a1 = 1*1 = 1 sq.unit.
20% increase in both sides, new area a2 = 1.2*1.2 = 1.44.
i.e, % increase in area = 1.44 - 1 = .44 or 44%.
a1 = 1*1 = 1 sq.unit.
20% increase in both sides, new area a2 = 1.2*1.2 = 1.44.
i.e, % increase in area = 1.44 - 1 = .44 or 44%.
Bhavik said:
6 years ago
Say length =100.
But it increased to 120.
Therefore the area of rectangle = 120*120 = 14400.
Now divide by 100-->144. So 144-100 = 44 is the answer.
But it increased to 120.
Therefore the area of rectangle = 120*120 = 14400.
Now divide by 100-->144. So 144-100 = 44 is the answer.
(5)
Kasaiah said:
9 years ago
Why all of them taking a length as 100 that and is not a square. Why don't you try it length and breadth with separate values like 100 & 200?
Ajmal said:
1 decade ago
@ Vijay
The difference between the original area = xy and 36/25 xy is
= (36/25)xy - xy
= xy(36/25 - 1)
= xy(11/25)
or
= (11/25)xy.
The difference between the original area = xy and 36/25 xy is
= (36/25)xy - xy
= xy(36/25 - 1)
= xy(11/25)
or
= (11/25)xy.
Deependra singh said:
9 years ago
Take length and breadth each 10 then area = 100.
Increased length and breadth will be 12 each then 12*12 = 144 increased area is 44 so 44%.
Increased length and breadth will be 12 each then 12*12 = 144 increased area is 44 so 44%.
Mero baduwal said:
8 years ago
Please solve the question that what percent changes in area of rectangular if there is mistake in length and breadth by one percent.
Chandra said:
1 decade ago
When there is an increase in sides of a figure, the net increase in its area is x+y+xy/100 %
So here 20% +20% + 20x20/100% = 44%
So here 20% +20% + 20x20/100% = 44%
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