In how many ways can 6coloured chalks be arranged if 2 are same colour?
Answer Details
If we have 6 different coloured chalks, we can arrange them in 6! = 720 ways. However, in this case, we have 2 chalks that are the same colour, which means we are double counting some arrangements.
To see how many arrangements we are double counting, imagine we label the two same-coloured chalks as A and A'. We can arrange the chalks in 6! ways, but for each of these arrangements, we can swap A and A' and get the same arrangement. So each arrangement is counted twice, and we need to divide by 2 to get the correct number of arrangements.
Therefore, the number of arrangements is 6!/2 = 360.
So the answer is (D) 360.