To find Ca / Rb we take Ra = 0 --- is this right?
I used mason's formula
P1 = -G2 G1 H1
Loop = G1, G2, -H1, -H2
Using Mason's Gain we get:
Delta1 = 1
Delta = 1 - G1G2H1H2
Using Mason's Gain
TF = -G1G2H1 Divided by ( 1 - G1G2H1H2)
But substituting the values I don't get the answer that matches any options.
The Attempt at a Solution
Substituting I get:
This gives answer in cube as second term of numerator will go in cube for s. None of options have s cube.
I think the options are wrong.
For left TF we get C(s)/R(s) = 10/11
For Right we get C(s)/R(s) = 5/3.5
Multiplying them doesn't give the answer