F.3 Maths
1 個解答
- 匿名1 十年前最愛解答
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 .