Your answer, "250", is not correct.
The correct answer to
How many cheif officers were over Solomon's work?
is
550
as shown by
1 Kings 9:23
which is
- KJV
- These were the chief of the officers that were over Solomon's work, five hundred and fifty, which bare rule over the people that wrought in the work.
- NIV
- They were also the chief officials in charge of Solomon's projects--550 officials supervising the men who did the work.