Answer
$ f_{B/A} = 0.14 $
Work Step by Step
To calculate the time the system spends in configuration B to the time it spends in configuration A, we use the following equation.
$ f_{B/A} = \frac{W_B}{W_A}$
Taking $W_A $ and $W_B$ from (d) and (e)
$ f_{B/A} = \frac{1.375 \times 10^{28}}{1.01 \times 10^{29}}$
$ f_{B/A} = 0.14 $
