Engineering Variation of parameters in this Diode-Resistor circuit

[mazeem]

Homework Statement

I have solved the following assignment (attached) but I have no idea if I have done it right or not? Feedback will be appreciated. It is from the Albert Malvino's Electronic Principles and is Fig. 3-25.
For each independent variable increase, determine what will be response of the dependent variables for the following circuit. Use 2nd approximation for diode.


Independent variables: Vs, R1, R2, R3, Vk
Dependent variables: Va, Vb, Vc, I1, I2, I3, P1, P2, P3.
Bonus Marks (3 marks)
Also calculate values of all the dependent variables for a 10% increase in all the independent variables.

Relevant Equations

V=IR,
P=VI
Vk=0.7 V

Circuit diagram

 

[scottdave]

It appears to me that the question is asking for the response of all dependent variables for change in each independent variable (while holding others constant).
Your solution appears to only address the 10% case. In that situation, it looks like you divided by 100k rather than 110k for I₃. Also, I believe Vk should also increase by 10%.

I'm not sure if the question is asking, but I think it would be useful to know what values cause the diode to turn off.