MATH x 2

The pigments are added into white paints to produce various colors and shades.

Cases for the 2 bursts are in different colours:
- number of combination for selecting 2 from the 4 colours:
　4C2 = 6
- for each colour, it may be either 10ml or 20ml bursts:
　2 x 2 = 4
Therefore, total number of cases = 6 x 4 = 24

Casese for the 2 bursts are in same colours:
- number of colours = 4
- the 2 bursts may be either: 10+10, 10+20 or 10+30 (3 options)
Therefore, total number of cases = 4 x 3 = 12

The machine can produce total 24+12 = 36 different colours and shades using exactly two bursts of pigment.

2007-02-16 09:23:57 補充：
題目係 put pigments into white paint, 同埋問 how many different colours and shades唔同份量既 pigments 加入白色油漆係會得出唔同深淺既顏色 (shades)

1 coata is using a machine that can put bursts of red ,yellow,blue or black pigments into white paint to produce various colours and shades.
the machine puts in either 10ml or 20ml bursts.
how many different colour and shades can costa produce using exactly two bursts of pigment?
The combinations for choosing two bursts of pigment from red ,yellow,blue or black pigments
=4C2
=6
each colour can put 10ml or 20ml
There are 4 combinations
So
The number of different colour and shades can costa produce using exactly two bursts of pigment
=6*4
=24

2007-02-15 15:26:06 補充：
Cases for the 2 bursts are in same colours:但題目是要different colours0甘點解你又要做li個case??