Question

If 20 men do a job in 48 days, how many women would be required to do thesame work for 30 days if the capacity of a man to woman is 2:3

Answer 1

The work is proportional to the product of power (or efficiency of workers) and time. The work is the same for both men and women:

$$W\equiv N_mt_m,\\ W\equiv \frac23N_wt_w.\\\space\\ N_mt_m=\frac23N_wt_w,\\\space\\ N_w=\frac32N_mt_m/t_w=48\text{ women}.$$