If half of the full time us workers moved to part time, how would the total cost of employees change for anchor global insurance?

The correct answer for the question that is being presented above is this one:
Based on the table that is shown from my research, 
As it stands now, the total cost in millions of dollars is:

47.0 + 2.5 = 49.5

Now, if half of the full-time workers become part time, then the total cost will be

= 47.0 * [(1740 − 0.5 * 1740) /1740] + 2.5 * [(170 + 0.5 * 1740) / 170]
= 23.50 + 15.29
= 38.79
Then the answer will be 38.79