等比数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\)，已知\(a_{2}a_{5}=2a_{3}\)，且\(a_{4}\)与\(2a_{7}\)的等差中项为\( \dfrac {5}{4}\)，则\(S_{5}=(\)　　\()\)