Apaya First of all, I don't speak Chinese so I wrote my post in English. Thank you for understanding me.
Hi! How are you guys doing? Are you guys having a good time with new op hunter Estelle? Sadly I am not because I spend 7200 mandas and didn't get her.
Below is my gacha result and I think this event is broken.
1★ 189 71.6%
2★ 47 17.8%
3★ 28 10.6%
4★ 0 0.0 %
Total of 264
Since the middle one always gives at least 3★ hunters, I subtract 24 from 3★ hunters and it gives way interesting results!
1★ 189 78.7%
2★ 47 19.6%
3★ 4 1.7 %
4★ 0 0.0 %
Total of 240
It shows the probability to get at least 3★ hunters is 1.7% which has to be around 6%.
Statistically, getting at most 4 at least 3★ hunters with 240 tries is only 0.1% which is not natural.
I want to know if you guys having similar result as I do.
Thank you for reading this and hope you guys catch her!
卡尔在觉醒 
SmileV 
Doginsea
Btw, I have some assumptions:
......1)Maybe Tier4 1% only works for newbie under lvl 30.
..... 2) For senior, I lay emphasis on tier3 firstly. If you had got 48Tier3/all 50 tier3 (i haven't count yet.) .
Then your tier3 droprate may be:
5%*(2/50)*0.6 + 5%*0.4
It approaches to 2% , that your article's 1.7% falls in acceptable error area.
....3) i don't know probability about 'enroll ticket' .(Different from Manda. IDK its engliah name.)
It works like another probability.
....4) New hero like Estella, 0.6%....., might be true, might be false.
I don't have enough database to prove it.
Only thing I know is, the Estella droprate for this enroll, newbie draw= senior draw.(only for Estella)