Consider the series: 5 G T 2 % 7 J K 9 B & M 4 R 8 D. Which element lies exactly midway between the third element from the left end and the fourth element from the right end?

The third from the left is T at place 3. The fourth from the right stands at place 16 − 4 + 1 = 13, the digit 4. The midpoint of places 3 and 13 is (3 + 13) ÷ 2 = 8, which holds K. Four elements (2 % 7 J) lie on one side of K and four (9 B & M) on the other. The 9 at place 9 and the J at place 7 are the one-place slips, and B at place 10 comes of taking the fourth from the right as the element at place 12.