[填空题]
The first three terms of a geometric sequp9ey 5xnm1ce)enc* ,8b a;amd9da*zzwad*lih; ue are $ 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 $S_{n}>35000$ .
