BJT Analysis Question: Solving for Vb with Voltage Divider Method

[eehelp150]

Homework Statement

Homework Equations

KVL

The Attempt at a Solution

This is the solution given:
VB = (VCC*30k)/(70k+30k) = 3V
Why is a voltage divider being used to find Vb?

 

[gneill]

Your question should be in the problem statement, not the attempt.

Are you sure that VB is the same as Vb? Looks to me like a determination of a Thevenin equivalent for the base voltage supply. Was there also a Thevenin resistance calculated (paralleling the 30 k and 70 k resistors)?

 

[eehelp150]

Your question should be in the problem statement, not the attempt.

Are you sure that VB is the same as Vb? Looks to me like a determination of a Thevenin equivalent for the base voltage supply. Was there also a Thevenin resistance calculated (paralleling the 30 k and 70 k resistors)?

VB is Vb.
Thevenin resistance was calculated for 30k and 70k.

 

[LvW]

What is your task? To find the DC voltage VB at the base?
Don`t forget that you have a loaded resistive voltage divider - loaded with the transistor base current.

 

[gneill]

This is what I imagine the author of the solution was going for:

With $V_B$ and $R_B$ being determined as the Thevenin equivalent of the base voltage divider.