[填空题]
The first three terms of a geometric sequenceod4 j r5iz tij27zqt,3 ar5afv) iyxthi:bcj9zx tlv3fxi 98s;xv+ 61 0de $ u_{1}=0.8, u_{2}=2.4, u_{3}=7.2 $.
1. Find the value of the common ratio, r .
2. Find the value of $S_{8}$ .
3. Find the least value of n such that $S_{n}>35000$ .