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by Ian Stewart » Sun Aug 24, 2008 6:48 pm
If we pack three of the same colour, we have four choices of colour. We also have two different sizes, so 8 possibilities in total.

If we pack three of different colours, we also have four choices, because we have four choices of which colour to *not* include (or you can just calculate 4C3 = 4). Again, we have two different sizes, so 8 possibilities in total.

Adding these two cases, 8+8 = 16.
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by gmattester » Sun Aug 24, 2008 7:42 pm
Ian Stewart wrote: If we pack three of different colours, we also have four choices, because we have four choices of which colour to *not* include (or you can just calculate 4C3 = 4). Again, we have two different sizes, so 8 possibilities in total.

Adding these two cases, 8+8 = 16.
Ian can you explain further. I am not clear with this step.
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by pepeprepa » Mon Aug 25, 2008 1:19 am
https://www.beatthegmat.com/combinations-t15973.html
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