Let T be a full binary tree with 8 leaves. (A full binary tree has every level full). Suppose two leaves a and b of T are chosen uniformly and independently at random. The expected value of the distance between a and b in T (i.e., the number of edges in the unique path between a and b) is (rounded off to 2 decimal places) _____.

Consider the following $$New-order$$ strategy for traversing a binary tree:

$$\,\,\,\,\,\,\, \bullet \,\,\,\,\,$$ Visit the root;
$$\,\,\,\,\,\,\, \bullet \,\,\,\,\,$$ Visit the right subtree using $$New-order;$$
$$\,\,\,\,\,\,\, \bullet \,\,\,\,\,$$ Visit the left subtree using $$New-order;$$

The New-order traversal of the expression tree corresponding to the reverse polish expression 3 4 * 5 - 2 ^ 6 7 * 1 + - is given by:

The number of ways in which the numbers $$1, 2, 3, 4, 5, 6, 7$$ can be inserted in an empty binary search tree, such that the resulting tree has height $$6,$$ is _____________.

$$Note:\,\,\,The\,\,height\,\,of\,\,a\,tree\,\,with\,\,a\,\,\sin gle\,\,node\,\,is\,\,0$$

Consider the expression tree shown. Each leaf represents a numerical value, which can either be 0 or 1. Over all possible choices of the values at the leaves, the maximum possible value of the expression represented by the tree is ___.