Question

Here is a rectangle ABCD. A B 20 cm D с 30 cm The length of the rectangle is increased by 10%. The width of the rectangle is increased by 5%. Find the percentage increase in the perimeter of the rectangle.

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Answer 1

8%

Explanation:

The original perimeter is 100cm

The 20cm is representative of the width

30cm is representative of the length

length is increased by 10%

30+(.10 x 30)

(1 + .10) × 30

(100% + 10%) × 30

110% × 30

110 ÷ 100 × 30

110 × 30 ÷ 100

3,300 ÷ 100

= 33

length is increased by 5%

20 + (5% × 20) =

20 + 5% × 20 =

(1 + 5%) × 20 =

(100% + 5%) × 20 =

105% × 20 =

105 ÷ 100 × 20 =

105 × 20 ÷ 100 =

2,100 ÷ 100 =

= 21

New perimeter: 108 cm

Percentage increase:

(108-100):100*100 =

(108:100-1)*100 =

108-100 = 8

= 8%