已知等差数列\(\{a _{n} \}\)的前\(n\)项和为\(S _{n}\)，等比数列\(\{b _{n} \}\)的前\(n\)项和为\(T _{n}\)，且\(a _{1} =b _{1} =1\)，\(a _{5} =S _{3}\)，\(a _{4} +b _{4} =15\)．
\((\)Ⅰ\()\)求数列\(\{a _{n} \}\)与\(\{b _{n} \}\)的通项公式；
\((\)Ⅱ\()\)求数列\(\{ \dfrac {S_{n}\cdot T_{n}}{n}\}\)的前\(n\)项和．