Q. 18

# The length of a rectangle is increased by 15% and the breadth is reduced by 15%. Let’s work out in percentage the increase or decrease of area.

Answer :

Given: The percentage increment of the length of the rectangle=15%

The percentage decrement of the breadth of the rectangle=15%

Tip: if y is increased by x% then the new value of y is

: if y is decreased by x%, then the new value of y is

Let the length of the rectangle be “L” units.

Let the breadth of the rectangle be B units

Therefore, initially before any change in the lengths of both the length and breadth of the rectangle is

=

Now, Using tip (i)

The new length of the rectangle will be:

=L units =L units

Now, Using tip (ii)

The new breadth of the rectangle will be:

=B units. =B units

Therefore, the new area of the rectangle will be:

=LB

=LB

Therefore, the decrement in area= LB- LB

=LB

Therefore, percentage decrement in area,

=

=

=2.25%

Rate this question :

(i) Rs. 2.25 out of Rs. 5

(ii) 85g out of 17 kg

(iii) 2.250 kg out of 0.72 quintal.

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