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a box contains sweets of 6 different flavours. There are at least 2 sweets of each flavour. A girl selects 3 sweets from the box. Given that these 3 sweet are not all of the same flavouor, calculate the no. of different ways she can select her 3 sweets.6C3 ways of secting 3 sweets altogether but 6 of these have all same colour so ans=6C3-6
6*5*4/6 =20 no two the same colour6*5*2/3=20 two the same colour40 ways altogether
my reasong for 6*5*2/3 is this: For the first you have a choice of 6 and for the second a choice of 5. For the tird you can have the first or second colour, hence the factor of 2 and divide by three because the odd colour can be 1st, 2nd, or third.