[填空题]
The size of the trunk diameter of a ches3issrm 2()*styhx7 emtnut oak trejouln5lxb )qyo aqu b )69/(7ee, $d$, in centimetres, can be modelled by the function
$d(t)=9ln(0.25t)$,t≥5,where $t$ is the age, in years, of the tree.
1.Find the size of the trunk diameter of a 10-year-old chestnut oak tree. d =
2.The size of the trunk diameter of a chestnut oak tree is 15 cm. Find its age. t =
A chestnut oak tree can be harvested for wood when the size of its trunk diameter reaches 20 cm.
3.Find the age of the chestnut oak tree when it is old enough to be harvested for timber. t =