To find out how many acres the group of workers can plant in 4 days, you can multiply their planting rate by the number of days:
\[ \text{Acres planted} = \text{Rate} \times \text{Days} \]
Here, the rate is 16 acres per day and the number of days is 4:
\[ \text{Acres planted} = 16 , \text{acres/day} \times 4 , \text{days} = 64 , \text{acres} \]
Therefore, the group of workers can plant 64 acres in 4 days.