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Count signals by their remaining colour multiplicities

Naval signals are made by arranging coloured flags in a vertical line and the flags are read from top to bottom. How many different signals can be made from 1 green, 3 red and 2 blue flags if

(i) all 6 of the flags are used,

(ii) at least 5 of them are used?

CJC · Discussion · Question 7

Same-colour flags are indistinguishable; split five-flag cases by the omitted colour.

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