Aptitude - Area - Discussion

@ : Home > Aptitude > Area > General Questions - Discussion

"Example is better than precept."

- (Proverb)

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:

[A].	10%	[B].	10.08%
[C].	20%	[D].	28%

Answer: Option A

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

Nani said: (Tue, Aug 16, 2011 05:03:39 PM)

Please explain clearly anyone of you.

Xyz said: (Thu, Sep 8, 2011 06:14:28 PM)

SANTHO your explanation short and sweet. But why we use x+y in all problems your formula will work or not?

Sabir said: (Mon, Dec 12, 2011 03:09:02 PM)

Nanii .. Let the original length be 100cm n d breadth be also 100 cm the lengths n breadths after washing will be 80 and 90 .. Original area= 100100 = 10000 cm2 New Area= 8090 = 7200 cm2 So percentage decrease = (10000-7200)/100 = 2800/100 = 28% :)