# 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:
10%
10.08%
20%
28%
Explanation:

Let original length = x and original breadth = y.

Decrease in area
 = xy - 80 x x 90 y 100 100
 = xy - 18 xy 25
 = 7 xy. 25

 Decrease % = 7 xy x 1 x 100 % = 28%. 25 xy

Discussion:
26 comments Page 1 of 3.

Akil said:   2 years ago
It is simple.

L(0.80)*B(0.90).
= LB(0.72).

So, 100 - 72= 28% loss.
(12)

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.
(2)

D.Mukul Raj said:   3 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.
(1)

Deepak virat said:   4 years ago
80*90/100 = 72.
As we see 28 is reduced so we can say that the percentage decrease is 28%.
(1)

OMARFARUK said:   4 years ago
Main formula +-p+-q+-(pq/100).

-20-10+(20* 10 / 100) = -28%.
(-ve) indicates area decrease.

Pinku said:   5 years ago
x=a*80/100
y=b*90/100

Area=x*y=80*a*90*b/100*100=72/100(a*b)
decreased area=total area(ab)-72ab/100
=ab-72ab/100
=100-72(ab/100)
=28/100(ab)
= 0 .28ab or 28ab%.

Decreased area by 28%.

Jatin said:   7 years ago
-20-10+20*10/100 = 28%.

Dhanraj said:   8 years ago
How 7/25 came there? Explain it.

Sreelu said:   8 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.
(1)

Islam Ansari said:   8 years ago
xy - 18/25xy.
= 7/25xy.

How?