F.1數學題1條(超急)

Let x kg be the volume of oil in the Large Bottle
Let y kg be the volume of oil in the Small Bottle

x+y = 4
y = 4-x ---------(1)

(1 - 1/4) x 3
-------------- = --- ------------(2)
y + 1/4 x 2

Sub (1) into (2)

(1 - 1/4) x 3
----------------- = ---
(4-x) + 1/4 x 2

2 * (1 - 1/4) x = 3 * [(4-x) + 1/4 x ]

2 * 3/4 x = 3 * [ 4 - 3/4 x ]

6/4 x = 12 - 9/4 x

15/4 x = 12

x = 48/15

x = 3.2

From (1) x + y = 4
(3.2) + y = 4
y = 0.8

Therefore, there is 3.2 kg of oil in the large bottle, and 0.8 kg in the small bottle.

2007-03-19 20:25:47 補充：
the spacing for (2) doesn't work, BE CAREFUL with the 3 and 2 at the end, those are equal to 3/2i hope u understand, both 3 and 2 are on the Right Hand Side!!

Let A be the original amount of oil in the small bottle
Let B be the original amount of oil in the big bottle

(1-1/4)xA : B+1/4xA = 3:2
ie. 3/4xA = 3/5 equation 1
1/4xA+B = 2/5 equation 2

make A the subject of Equation 1
A=(3/5)/(3/4)

subscribe Equation 1 into Equation 2
1/4x[(3/5)/(3/4)]+B=2/5
B=2/5-1/4x[4/5]
B=2/5-1/5
B=1/5

therefore the roiginal amount of oil in the small bottle is 1/5 of 4kg = 0.8kg.

2007-03-19 20:36:06 補充：
又慢左....

x = 3.2
y = 0.8

A MINUS 1 OVER 4 OVER 3 = B OVER 2