See
Initialy table is empty so 1st element is inserted with Probebility = $\frac{m}{(m)} = 1$
2nd elemnt witll inserted into two places either just before 1st element and just after first element so choice= $\frac{3}{(m)}$
3rd element will have only one choce i.e. 1st time coliision then 2nd time collision then get its place using liener fashion = 1/m posiblity.
Total = $\frac{3}{(m)(m)}$