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    1 十年前
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    1)

    (a)

    Maximum absolute error

    = 0.5 cm

    (b)

    ( ABCDEF is with minimum area when AB = 17.5cm , BC = 11.5cm , DE = 1.5cm , EF = 14.5cm )

    The least possible area of the metal sheet

    = 17.5 x 13 - 3 x 1.5

    = 227.5 - 4.5

    = 223 cm^2

    2)

    As I can only read part (b) of the question , if solid X and solid Y are similar with linear ratio 1 : 2 , then solid X' and solid Y' are similar too .

    3)

    The height of the street lamp is about 3.75 m .

    I use a ruler to measure the height of the little girl appear on the photo , which is 2cm . Then I measure the height of the street lamp appear on the photo , which is 3.5cm . As the height of the little girl and the height of that appear on the photo are in ratio , if the height of the street lamp is y m ,

    y / 3.5 = 1 / 2

    y = 3.75

    Then we can estimate the height of the street lamp , which is about 3.75 m .

    4)

    (a)

    The least possible length of the metal wire

    = ( 5 - 0.5 ) cm

    = 4.5 cm

    (b)(i)

    Maximum absolute error = 0.1 / 2 m = 0.05 m

    The most possible length of the metal wire

    = ( 2.0 + 0.05 ) m

    = 2.05 m

    = 205 cm

    which is less than 206 cm .

    Therefore , it is impossible that the actual length of this metal wire exceeds 206 cm .

    (ii)

    195 cm < actual length of the metal wire < 205 cm

    195 / 46 cm < actual length of each short metal wire < 205 / 46 cm

    4.239 cm < actual length of each short metal wire < 4.457 cm

    The actual length of each short metal wire does not reach 4.5 cm .

    Therefore , it is impossible to do this .

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