A small business producing a seasonal product began the calendar year with 15 employees. Listed below are the changes to their staff throughout the year:
On April 1st, the business hired 6 employees.
On May 1st, the business laid off 7 employees.
On August 1st, the business laid off 8 employees.
On November 1st, the business hired 10 employees.
What was the average number of employees on the payroll during the calendar year? Assume that each month has the same length.
Note: Please make sure your final answer(s) are accurate to 1 decimal place