( 列識）
The shape of the lateral surface of a right prism (Multiple Choice )
A . must be a square
B . must be a trapezium
C . must be a rectangle .
D . cannot be determined
20.Given that x + y=39 and x : y=4:9
a) For the expression x:y =4:9 , express xin terms of y .
b) Hence , find the value of xand y.
14. The ratio of the wight of tin and zinc in a 112kg alloy is 5 : 2 . Find the wight of tin in the alloy .
Maths ( 列識）
2007-04-09 10:21 pm
回答 (1)
2007-04-09 10:52 pm
✔ 最佳答案
The shape of the lateral surface of a right prism (Multiple Choice )B . must be a trapezium
20.
a) x: y = 4:9
x/y = 4/9
(x/y)(y) = (4/9)(y)
x= 4y/9
b)
x + y = 39
(4y/9) + y = 39
13y/9 = 39
y = 27
As x + y = 39
x = 39 -y = 39- 27 = 12
therefore, x = 12, y =27
14. weight of tin
= 112 kg x [ 5/ (5+2) ]
= 80 kg
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