BJT analysis question

1. Oct 31, 2016

eehelp150

1. The problem statement, all variables and given/known data

2. Relevant equations
KVL

3. 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?

2. Oct 31, 2016

Staff: Mentor

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)?

3. Oct 31, 2016

eehelp150

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

4. Nov 1, 2016

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.

5. Nov 1, 2016

Staff: Mentor

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.