What is the formula for calculating the average period for calculating interest on a partner's drawings?

(Months left after Ist drawing + Months left after last drawing) / 2

The correct answer is option 1- (Months left after Ist drawing + Months left after last drawing) / 2.

When a fixed amount of money is withdrawn by the partners, at equal time interval, say each month or each quarter, the average period is calculated to know the interest on drawings.

The formula for calculating the average period is = (Months left after Ist drawing + Months left after last drawing) / 2.

After calculating the average period interest on drawings is calculated. The formula for calculating interest on drawing is = Total drawings X (Rate of interest/100) X )Average period/12)