The average number of post graduate employees in offices B, D and E is approximately what per cent of the total number of female employees in offices A, C and F?

Female employees in,
A = $$\frac{3}{7}\times\ 1680\ =\ 720$$
C = $$\frac{11}{23}\times\ 2760\ =\ 1320$$
F = $$\frac{15}{28}\times\ 2240=1200$$.
Total Female employees in A,C and F = 3240.

Post graduate employees in,
B = 0.65*2160 = 1404
D = 0.55*2340 = 1287
E = 0.60*2520 = 1512.
Total Post Graduate employees in B, D and E = 4203 and Average = $$\frac{4203}{3}=1401$$.

Required percentage = $$\frac{1401}{3240}\times\ 100=43.24\%$$.