Question

Suppose, you have two shorts, one is black and the other one is blue; three shirts which are in white, blue and red. You again wish to make different combinations, but you always want to make sure that the shorts and shirt that you wear are of different colours. List and check how many combinations are possible now

Answer 1

We have given two shorts which are black and blue in colour.

Take it as T black and T blue.

Also, we have 3 shirts, coloured white, blue and red denoted by S white, S blue and S red.

Now fix T black and then T blue the different combinations are 

Thus we get a total of 6 combinations as

Black short and White shirt

Black short and Blue shirt

Black short and Red shirt

Blue short and White shirt

Blue short and Blue shirt

Blue short and Red shirt.

But it is given short and the shirt is of different colours.

We give up Blue short and Blue shirt combination.

So we have 5 different combinations.