Mr Chan has 9 marbles of different colours. Find the number of arrangements in each of the following cases.
a) He divides the marbles into 3 groups: 2 marbles, 3 marbles and 4 marbles
b) He gives the marbles to his 3 sons. One gets 2 marbles, one gets 3 marbles and one gets 4 marbles.
分唔到2條問題有甚麼不同