Explanation:

- When a partner withdraws a fixed amount quarterly on the last day, the interest calculation involves averaging out the effect of withdrawals over the year.

Average period = Months after 1st drawing + months after last drawings/2 = 9 + 0/2 = 4.5 months

First drawing is made after end of first quater so months left = 9 months

Last drawing is done at the end of the last quater(last day of year), so months left = 0 months