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Mathematics Question : 2). The figure shows a square of side 15cm. If each side is increased by 20%, find

(a) the new length of each side,

(b) (i) the percentage increase in perimeter,

(ii) the percentage increase in area.

Please explain how to calculate, if you can please translate to Chinese. Thank You! Please reply me tonight, because tomorrow I need bring it back to school pass to my teacher.

2 Answers

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  • Anonymous
    1 decade ago
    Favorite Answer

    Q: The figure shows a square of side 15 cm . If each side is increased

    by 20%, find

    ( a ) the new length of each side

    ( bi ) the percentage increase in perimeter

    ( bii ) the percentage increase in area

    有一個正方形的邊長為 15 公分 . 若每邊增加 20%. 求

    ( a ) 新的邊長

    ( bi ) 周長增加的百分比

    ( bii ) 面積增加的百分比

    Sol:

    ( a )

    15 * ( 1 + 20% )

    = 15 * 1.2

    = 18

    ( bi )

    original perimeter ~

    15 * 4 = 60

    new perimeter ~

    18 * 4 = 72

    72 ÷ 60 - 1

    = 1.2 - 1

    = 0.2

    = 20%

    P.S 邊長增加的百分比 = 周長增加的百分比.

    ( bii )

    original perimeter ~

    15 * 15 = 225

    new perimeter ~

    18 * 18 = 324

    324 ÷ 225 - 1

    = 1.44 - 1

    = 0.44

    = 44%

    Ans: ( a ) 18 cm ( bi ) 20% ( bii ) 44%

    Send me a letter and tell me which step if you don’t understand.

    Source(s): 數學小頭腦
  • Anonymous
    1 decade ago

    ( a )

    15 * ( 1 + 20% )

    = 15 * 1.2

    = 18

    ( bi )

    original perimeter ~

    15 * 4 = 60

    new perimeter ~

    18 * 4 = 72

    72 ÷ 60 - 1

    = 1.2 - 1

    = 0.2

    = 20%

    ( bii )

    original perimeter ~

    15 * 15 = 225

    new perimeter ~

    18 * 18 = 324

    324 ÷ 225 - 1

    = 1.44 - 1

    = 0.44

    = 44%

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