Please show work for the problem below:

In a study of people's work habits, 16 traders at an international bank were chosen at random, and the number of hours they worked during one month was recorded. It was determined that the average number of hours worked per person was 200. If 12 of the people worked an average of 190 hours each during the month, how many hours did the other four people average?

a)200

b)210

c)220

d)230

e) 240