transistor biasing

Hi everyone

I am trying biasing a transistor using voltage divider.I can calculate everything on this schema except Re resistor ! How can i calculate it ?

Here is my wrong calculation ??

Accoprding to your first attachement VBB is NOT the base voltage. It is the equivalent Thevenian voltage.
Instead: VB(base)=VBB-IB*RB=1.17 volts. This results in RE=470 ohms.

Thanks now i understood )

You cannot buy a transistor with an hFE of 100. They have a range of hFE.
The hFE of a common 2N3904 transistor is from 100 to 300 (each transistor is different even with the same part number) when the collector current is 10mA and is a minimum of 70 when the collector current is 1mA. So the base voltage divider should have more current than you have, 10 times the typical base current. The typical base current is 1mA/100= 10uA so the divider current should be about 100uA (a total of 100k ohms).
Then a transistor with a minimum hFE will be biased almost correctly and a transistor with a maximum hFE will be biased almost correctly.

Your circuit has resistor values for its voltage divider that are too high so a transistor with minimum hFE will not be biased correctly.