Question 979496
A=Ao{1+r}^t; t=hours
10000=9000(l+r)^t
divide by 9000 and take ln of both sides
ln (10/9)=t ln (1+r)
0.1054=ln(1+r)
raise both sides to e power
1.111=1+r
r=0.111 or 11.1%

ln2=t ln (1.111)
0.693=t * 0.10536
t=6.578 hours or about 6 hours 35 minutes

Check:
1.111^6.578=2