[問題]GWD24-19

[magic]

19
Color X ink is created by blending red, blue, green, and yellow inks in the ratio 6:5:2:2. what is the number of liters of green ink that was used to create a certain batch of color X ink?
(1)The amount of red ink used to create the batch is 2 liters more than the amount of blue ink used to create the batch.
(2)The batch consists of 30 liters of color X ink.
答案是D
我絕得是B耶
為什麼A可以單獨解題勒

[kwtluck]

red:blue:green:yellow = 6:5:2:2

條件一給red=blue+2................(1)
又已知red:blue=6:5=>5red=6blue....(2)
(1)(2)聯立可求解,再帶回比例即可得green
所以條件一也符合

[magic]

謝謝喔

[daphnejw]

red:blue:green:yellow = 6:5:2:2

條件一給red=blue+2................(1)
又已知red:blue=6:5=>5red=6blue....(2)
(1)(2)聯立可求解,再帶回比例即可得green
所以條件一也符合

請問(1)如何獨立解出答案呢?
大大回覆的是(1)(2)聯立可求解,
那答案不就變成C了?

[vantreal]

其實可以用比例法:

red:blue:green:yellow = 6:5:2:2
total ink (all colors added up)= 15

total: x liters
red liters= (red/total) times x =6x/15
blue liters=(blue/total) times x=5x/15
difference= 6x/15- 5x/15=2,
so x = 30

which is the same as (2)

[bevisfan]

我覺得這樣看比較簡單
r:b:g:y = 6:5:2:2
set r=6t liters,
b=5t liters
by(1)
r=2+b
6t=2+5t => t = 2
g = 2t=2*2=4 sufficient

by(2)
r+b+g+y=30
total is 15t=30 => t=2
後面一樣 sufficient

answer is D[/b]