Correct choice is (a) \(\frac{\tilde{\phi_f}-\tilde{\phi_c}}{1-\tilde{\phi_c}}\)
Best explanation: The Downwind Weighing Factor is given by
DWFf=\(\frac{\phi_f-\phi_c}{\phi_d-\phi_c}\)
Normalizing this, we get
DWFf=\(\frac{\tilde{\phi_f}-\tilde{\phi_c}}{\tilde{\phi_d}-\tilde{\phi_c}}\)
But, the value of \(\tilde{\phi_d}\) is 1. So,
DWFf=\(\frac{\tilde{\phi_f}-\tilde{\phi_c}}{1-\tilde{\phi_c}}\)