Solution:

(i) According to the question, if the couple has two children then the sample space is:

Assume A denotes the event of both children having male children, and B denotes the event of at least one of the male children having male children.

As a result, we have:

Hence,

By substituting the values we get

(ii) Assume that represents the event of having both female children and D represents the event of having a female elder child.

And,

Hence,