If 3 hens lay 4 eggs in 5 days, how many days would it take a dozen hens to lay 8 dozen eggs?

3 hens lay 4 eggs in 5 days;

then, 3 hens lay 4 * 24eggs = 8 dozen eggs in 5 * 24 days = 120 days;

then, 3 * 4 hens = 12 hens lay 8 dozen eggs in 3 * 120 = 360 days;

Finally, a dozen hens lay 8 dozen eggs in 360 days = 1 year;