Aptitude - Area - Discussion
Discussion Forum : Area - General Questions (Q.No. 7)
7.
A towel, when bleached, was found to have lost 20% of its length and 10% of its breadth. The percentage of decrease in area is:
Answer: Option
Explanation:
Let original length = x and original breadth = y.
| Decrease in area |
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 Decrease % = |
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7 | xy x | 1 | x 100 |  % |
= 28%. |
| 25 | xy |
Discussion:
28 comments Page 1 of 3.
Akil said:
3 years ago
It is simple.
L(0.80)*B(0.90).
= LB(0.72).
So, 100 - 72= 28% loss.
L(0.80)*B(0.90).
= LB(0.72).
So, 100 - 72= 28% loss.
(14)
Kpkakadiya said:
3 years ago
Let L=10, B=10.
area = 10 * 10 = 100.
Now after bleached,
L = 80% of L
= 80% of 10,
= 8.
B= 90% of B,
= 90% of 10.
= 9.
Area = 8*9 = 72.
Decrease of area in % = (100 - 72 * 100)/100.
= 28.
area = 10 * 10 = 100.
Now after bleached,
L = 80% of L
= 80% of 10,
= 8.
B= 90% of B,
= 90% of 10.
= 9.
Area = 8*9 = 72.
Decrease of area in % = (100 - 72 * 100)/100.
= 28.
(4)
D.Mukul Raj said:
4 years ago
According to me, the solution is;
Suppose initial size = 120(L) x 110(B) = 13200.
and,
The towel shrunk down to 100(L) x 100(B) =10000.
so difference should be 13200-10000= 3200.
And if I divide 3200 by 13200 why am i getting the decreased area to be ( 8/33 ) ie 24.24242%.
Am I right? Please anyone clarify.
Suppose initial size = 120(L) x 110(B) = 13200.
and,
The towel shrunk down to 100(L) x 100(B) =10000.
so difference should be 13200-10000= 3200.
And if I divide 3200 by 13200 why am i getting the decreased area to be ( 8/33 ) ie 24.24242%.
Am I right? Please anyone clarify.
(2)
Vinayak Nayak said:
6 months ago
Consider L = 10 and breadth = 10
Then 20% less in length = 8 and 10% in breadth = 9.
now area = l * b= 8 * 9 = 72,
total area = 100,
new area = 100-72=28.
Then 20% less in length = 8 and 10% in breadth = 9.
now area = l * b= 8 * 9 = 72,
total area = 100,
new area = 100-72=28.
(1)
Deepak virat said:
5 years ago
80*90/100 = 72.
As we see 28 is reduced so we can say that the percentage decrease is 28%.
As we see 28 is reduced so we can say that the percentage decrease is 28%.
(1)
Sreelu said:
9 years ago
There is another simple method.
Let's assume L = 10 and B = 10.
Then area will be 100 (L * B).
When L lost 20% it gets the value 8.
Like that, B lost 10% it gets the value of 9.
So, the new area is 72 i.e (8 * 9).
Then % decrease = 100 - 72 = 28.
Let's assume L = 10 and B = 10.
Then area will be 100 (L * B).
When L lost 20% it gets the value 8.
Like that, B lost 10% it gets the value of 9.
So, the new area is 72 i.e (8 * 9).
Then % decrease = 100 - 72 = 28.
(1)
Sriram said:
1 decade ago
So simple by a formula.
x% decrease in length y% decrease in breadth then area change is -x-y+(x*y)/100.
x% decrease in length y% decrease in breadth then area change is -x-y+(x*y)/100.
(1)
Niks said:
6 days ago
Let's assume l is 100 and b is 30. (b remains less than l).
So, area = l*b= 100*30=3000.
Now, 20% decrease in l is 20%of 100=20, and 10% decrease in b is 10%of 30=3
l = 100-20=80;
b = 30-3 = 27
Area= 80 * 27 = 2160.
% decrease = total-area decreased/total = 3000-2160/300*100 = 28%
So, area = l*b= 100*30=3000.
Now, 20% decrease in l is 20%of 100=20, and 10% decrease in b is 10%of 30=3
l = 100-20=80;
b = 30-3 = 27
Area= 80 * 27 = 2160.
% decrease = total-area decreased/total = 3000-2160/300*100 = 28%
Santho said:
1 decade ago
x+y-(x*y/100)
Then, 20% + 10%-[20*10/100] = 28%
Then, 20% + 10%-[20*10/100] = 28%
OMARFARUK said:
5 years ago
Main formula +-p+-q+-(pq/100).
-20-10+(20* 10 / 100) = -28%.
(-ve) indicates area decrease.
-20-10+(20* 10 / 100) = -28%.
(-ve) indicates area decrease.
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